commit: Do not raise error when listing tree entries for nonexistent ref
The GetTreeEntries RPC has weird calling semantics: when the caller requests entries for a nonexisteng revision or path, then it won't error but instead just returns an empty set. While the rewrite for recursive listings introduced via 08507b22 (commit: Convert GetTreeEntries to use git-ls-tree(1), 2021-11-08) correctly honors the case when trying to list entries for an object which is not a treeish, it fails to do the same when using an invalid revision. As a result, the new code returns errors where we previously just silently failed.
Fix this by swallowing lstree.ErrNotExist
errors.
Changelog: fixed
Unblocks #3915 (closed)
Edited by Patrick Steinhardt