if username has spaces or is long, tempdir replaces username with tilde (`~`) (breaks pdflatex)

Summary:

Error when trying to insert LaTeX formula using Extensions->Render->LaTeX Formula in Inkscape.

Steps to reproduce:

• open Inkscape
• Click Extensions->Render->LaTeX Formula.
• When "use" is pressed a new window is launched.

What happened?

• The new window says: "Inkscape has received additional data from the script executed. The script did not return an error, but this may indicate the results will not be as expected."
• In the tex area below it says:

"Traceback (most recent call last):
  File "pdflatex.py", line 83, in <module>
    PdfLatex().run()
  File "C:\Program Files\Inkscape\share\inkscape\extensions\inkex\base.py", line 123, in run
    self.save_raw(self.effect())
  File "C:\Program Files\Inkscape\share\inkscape\extensions\inkex\extensions.py", line 159, in effect
    for child in fragment:
  File "pdflatex.py", line 49, in generate
    call('pdflatex', tex_file,\
  File "C:\Program Files\Inkscape\share\inkscape\extensions\inkex\command.py", line 182, in call
    return _call(program, *args, **kwargs)
  File "C:\Program Files\Inkscape\share\inkscape\extensions\inkex\command.py", line 171, in _call
    raise ProgramRunError("Return Code: {}: {}\n{}\nargs: {}".format(
inkex.command.ProgramRunError: Return Code: 1: b''
b"This is pdfTeX, Version 3.14159265-2.6-1.40.21 (MiKTeX 20.7)\r\nentering extended mode\r\n! I can't find file `C:/Users/ESPENM'.\r\n<to be read again> \r\n                   \\protect \r\n<*> C:/Users/ESPENM~\r\n                    1/AppData/Local/Temp/inktmpbw2nsret/input.tex\r\nPlease type another input file name: \r\n! Emergency stop.\r\n<to be read again> \r\n                   \\protect \r\n<*> C:/Users/ESPENM~\r\n                    1/AppData/Local/Temp/inktmpbw2nsret/input.tex\r\n!  ==> Fatal error occurred, no output PDF file produced!\r\nTranscript written on C:\\Users\\ESPENM~1\\AppData\\Local\\Temp\\inktmpbw2nsret\\texpu\r\nt.log.\r\n"
args: ['C:\\Users\\Espen Myrset\\AppData\\Local\\Programs\\MiKTeX\\miktex\\bin\\x64\\pdflatex.exe', '-output-directory=C:\\Users\\ESPENM~1\\AppData\\Local\\Temp\\inktmpbw2nsret', '-halt-on-error', 'C:\\Users\\ESPENM~1\\AppData\\Local\\Temp\\inktmpbw2nsret\\input.tex']"

Edited for readability:
b"This is pdfTeX, Version 3.14159265-2.6-1.40.21 (MiKTeX 20.7)
entering extended mode
! I can't find file `C:/Users/ESPENM'.
<to be read again> 
                   \\protect 
                   <*> C:/Users/ESPENM~
                    1/AppData/Local/Temp/inktmpbw2nsret/input.tex
                    Please type another input file name: 
! Emergency stop.
<to be read again> 
                   \\protect 
                   <*> C:/Users/ESPENM~
                    1/AppData/Local/Temp/inktmpbw2nsret/input.tex
                    !  ==> Fatal error occurred, no output PDF file produced!
Transcript written on C:\\Users\\ESPENM~1\\AppData\\Local\\Temp\\inktmpbw2nsret\\texpu
t.log.
"
args: ['C:\\Users\\Espen Myrset\\AppData\\Local\\Programs\\MiKTeX\\miktex\\bin\\x64\\pdflatex.exe', '-output-directory=C:\\Users\\ESPENM~1\\AppData\\Local\\Temp\\inktmpbw2nsret', '-halt-on-error', 'C:\\Users\\ESPENM~1\\AppData\\Local\\Temp\\inktmpbw2nsret\\input.tex']"

What should have happened?

A box with a LaTeX formula inside should be created in the document.

Sample attachments:

sample_attachment.txt:

Version Info:

- Inkscape Version: Inkscape 1.0 (4035a4fb49, 2020-05-01)
- Operating System: Windows 10 Pro
- Operating System version: 2004