Bug#992308: freecad: addon manager locks up on "Install/update selected"

[Alexis Lockwood]

Package: freecad
Version: 0.19.1+dfsg1-2
Severity: important
X-Debbugs-Cc: alexislockwood at fastmail.com

Dear Maintainer,

When the "Install/update selected" button is pressed in the Addon Manager,
FreeCAD locks up for me. Specifically, I selected the Assembly4 workbench,
which was not previously installed.

If FreeCAD is launched from a terminal, an error message is visible there:

```
Traceback (most recent call last):
  File "/usr/share/freecad/Mod/AddonManager/addonmanager_workers.py", line 769,
in run
    repo = git.Repo.clone_from(self.repos[idx][1], clonedir)
AttributeError: module 'git' has no attribute 'Repo'
```

However, no message is displayed in the UI, it just becomes unresponsive.

This appears to have been reported upstream before on a different distribution
and they blamed the distro package:
https://tracker.freecadweb.org/view.php?id=4072

The official 0.19 AppImage download directly from FreeCAD does not exhibit this
issue.

There is probably a secondary bug here that could be reported upstream about
the UI locking up when this error occurs, but it was mentioned in the linked
report already.


-- System Information:
Debian Release: 11.0
  APT prefers stable-security
  APT policy: (500, 'stable-security'), (500, 'stable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 5.10.0-8-amd64 (SMP w/8 CPU threads)
Kernel taint flags: TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE not
set
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages freecad depends on:
ii  freecad-python3  0.19.1+dfsg1-2

Versions of packages freecad recommends:
ii  calculix-ccx  2.17-3
ii  graphviz      2.42.2-5

Versions of packages freecad suggests:
pn  povray  <none>