Make version manage script run without an app version

Closes: #1641 (closed)

Before this MR

$ scripts/manage_version.rb --include-subcharts --chart-version 2.4.7
# New Versions
# version: 2.4.7
Reading /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/gitlab-exporter/Chart.yaml
Reading /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/migrations/Chart.yaml
Reading /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/gitaly/Chart.yaml
Reading /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/gitlab-shell/Chart.yaml
Reading /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/sidekiq/Chart.yaml
Reading /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/task-runner/Chart.yaml
Reading /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/mailroom/Chart.yaml
Reading /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/operator/Chart.yaml
Reading /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/gitlab-grafana/Chart.yaml
Reading /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/unicorn/Chart.yaml
Traceback (most recent call last):
        10: from scripts/manage_version.rb:228:in `<main>'
         9: from scripts/manage_version.rb:228:in `new'
         8: from scripts/manage_version.rb:128:in `initialize'
         7: from scripts/manage_version.rb:167:in `populate_subchart_versions'
         6: from scripts/manage_version.rb:167:in `map'
         5: from scripts/manage_version.rb:168:in `block in populate_subchart_versions'
         4: from scripts/manage_version.rb:168:in `new'
         3: from /home/balasankarc/work/charts/gitlab/scripts/lib/version_fetcher.rb:9:in `initialize'
         2: from /home/balasankarc/work/charts/gitlab/scripts/lib/version_fetcher.rb:9:in `new'
         1: from /home/balasankarc/work/charts/gitlab/scripts/lib/version.rb:16:in `initialize'
/home/balasankarc/work/charts/gitlab/scripts/lib/version.rb:16:in `initialize': no implicit conversion of nil into String (TypeError)

After this MR

$ scripts/manage_version.rb --include-subcharts --chart-version 2.4.7
# New Versions
# version: 2.4.7
Reading /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/gitlab-exporter/Chart.yaml
Reading /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/migrations/Chart.yaml
Reading /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/gitaly/Chart.yaml
Reading /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/gitlab-shell/Chart.yaml
Reading /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/sidekiq/Chart.yaml
Reading /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/task-runner/Chart.yaml
Reading /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/mailroom/Chart.yaml
Reading /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/operator/Chart.yaml
Reading /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/gitlab-grafana/Chart.yaml
Reading /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/unicorn/Chart.yaml
Reading /home/balasankarc/work/charts/gitlab/Chart.yaml
Updating /home/balasankarc/work/charts/gitlab/Chart.yaml
Updating /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/gitlab-exporter/Chart.yaml
Updating /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/migrations/Chart.yaml
Updating /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/gitaly/Chart.yaml
Updating /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/gitlab-shell/Chart.yaml
Updating /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/sidekiq/Chart.yaml
Updating /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/task-runner/Chart.yaml
Updating /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/mailroom/Chart.yaml
Updating /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/operator/Chart.yaml
Updating /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/gitlab-grafana/Chart.yaml
Updating /home/balasankarc/work/charts/gitlab/charts/gitlab/charts/unicorn/Chart.yaml
Complete


$ git diff

diff --git a/Chart.yaml b/Chart.yaml
index 8b2ab1e0..48a3d6ce 100644
--- a/Chart.yaml
+++ b/Chart.yaml
@@ -1,7 +1,7 @@
 ---
 apiVersion: v1
 name: gitlab
-version: 2.4.6
+version: 2.4.7
 appVersion: master
 description: Web-based Git-repository manager with wiki and issue-tracking features.
 keywords:
diff --git a/charts/gitlab/charts/gitaly/Chart.yaml b/charts/gitlab/charts/gitaly/Chart.yaml
index c882f5b8..f9c4922b 100644
--- a/charts/gitlab/charts/gitaly/Chart.yaml
+++ b/charts/gitlab/charts/gitaly/Chart.yaml
@@ -1,7 +1,7 @@
 ---
 apiVersion: v1
 name: gitaly
-version: 2.4.6
+version: 2.4.7
 appVersion: master
 description: Git RPC service for handling all the git calls made by GitLab
 keywords:
diff --git a/charts/gitlab/charts/gitlab-exporter/Chart.yaml b/charts/gitlab/charts/gitlab-exporter/Chart.yaml
index 6ab77f5a..2d0a993b 100644
--- a/charts/gitlab/charts/gitlab-exporter/Chart.yaml
+++ b/charts/gitlab/charts/gitlab-exporter/Chart.yaml
@@ -1,7 +1,7 @@
 ---
 apiVersion: v1
 name: gitlab-exporter
-version: 2.4.6
+version: 2.4.7
 appVersion: 5.0.1
 description: Exporter for GitLab Prometheus metrics (e.g. CI, pull mirrors)
 keywords:
diff --git a/charts/gitlab/charts/gitlab-grafana/Chart.yaml b/charts/gitlab/charts/gitlab-grafana/Chart.yaml
index c9ea7483..bf087cca 100644
--- a/charts/gitlab/charts/gitlab-grafana/Chart.yaml
+++ b/charts/gitlab/charts/gitlab-grafana/Chart.yaml
@@ -1,7 +1,7 @@
 ---
 apiVersion: v1
 name: gitlab-grafana
-version: 2.4.6
+version: 2.4.7
 description: Adapt the Grafana chart to interface to the GitLab App
 keywords:
 - gitlab
diff --git a/charts/gitlab/charts/gitlab-shell/Chart.yaml b/charts/gitlab/charts/gitlab-shell/Chart.yaml
index 5bbd4626..97d5ba32 100644
--- a/charts/gitlab/charts/gitlab-shell/Chart.yaml
+++ b/charts/gitlab/charts/gitlab-shell/Chart.yaml
@@ -1,7 +1,7 @@
 ---
 apiVersion: v1
 name: gitlab-shell
-version: 2.4.6
+version: 2.4.7
 appVersion: master
 description: sshd for Gitlab
 keywords:
diff --git a/charts/gitlab/charts/mailroom/Chart.yaml b/charts/gitlab/charts/mailroom/Chart.yaml
index 92ad4687..f06afaab 100644
--- a/charts/gitlab/charts/mailroom/Chart.yaml
+++ b/charts/gitlab/charts/mailroom/Chart.yaml
@@ -1,7 +1,7 @@
 ---
 apiVersion: v1
 name: mailroom
-version: 2.4.6
+version: 2.4.7
 appVersion: master
 description: Handling incoming emails
 keywords:
diff --git a/charts/gitlab/charts/migrations/Chart.yaml b/charts/gitlab/charts/migrations/Chart.yaml
index e62d7ac0..49679f53 100644
--- a/charts/gitlab/charts/migrations/Chart.yaml
+++ b/charts/gitlab/charts/migrations/Chart.yaml
@@ -1,7 +1,7 @@
 ---
 apiVersion: v1
 name: migrations
-version: 2.4.6
+version: 2.4.7
 appVersion: master
 description: Database migrations and other versioning tasks for upgrading Gitlab
 keywords:
diff --git a/charts/gitlab/charts/operator/Chart.yaml b/charts/gitlab/charts/operator/Chart.yaml
index f5ddd634..cf3acdaf 100644
--- a/charts/gitlab/charts/operator/Chart.yaml
+++ b/charts/gitlab/charts/operator/Chart.yaml
@@ -1,7 +1,7 @@
 ---
 apiVersion: v1
 name: operator
-version: 2.4.6
+version: 2.4.7
 appVersion: master
 description: Gitlab operator for managing upgrades
 keywords:
diff --git a/charts/gitlab/charts/sidekiq/Chart.yaml b/charts/gitlab/charts/sidekiq/Chart.yaml
index 4c36eae9..12f9f113 100644
--- a/charts/gitlab/charts/sidekiq/Chart.yaml
+++ b/charts/gitlab/charts/sidekiq/Chart.yaml
@@ -1,7 +1,7 @@
 ---
 apiVersion: v1
 name: sidekiq
-version: 2.4.6
+version: 2.4.7
 appVersion: master
 description: Gitlab Sidekiq for asynchronous task processing in rails
 keywords:
diff --git a/charts/gitlab/charts/task-runner/Chart.yaml b/charts/gitlab/charts/task-runner/Chart.yaml
index b7186d16..099c8711 100644
--- a/charts/gitlab/charts/task-runner/Chart.yaml
+++ b/charts/gitlab/charts/task-runner/Chart.yaml
@@ -1,7 +1,7 @@
 ---
 apiVersion: v1
 name: task-runner
-version: 2.4.6
+version: 2.4.7
 appVersion: master
 description: For manually running rake tasks through kubectl
 keywords:
diff --git a/charts/gitlab/charts/unicorn/Chart.yaml b/charts/gitlab/charts/unicorn/Chart.yaml
index 0ccf931e..1fb14184 100644
--- a/charts/gitlab/charts/unicorn/Chart.yaml
+++ b/charts/gitlab/charts/unicorn/Chart.yaml
@@ -1,7 +1,7 @@
 ---
 apiVersion: v1
 name: unicorn
-version: 2.4.6
+version: 2.4.7
 appVersion: master
 description: HTTP server for Gitlab
 keywords: