GitDiffFileProvider: execute single program processes to allow errored exits to be caught

[Slamdunk]

This PR:

• Covered by tests

Fixes #1719

When git is not installed in the system

Before

$ vendor/bin/infection --git-diff-lines

 [OK] No files in diff found, skipping mutation analysis.

After

$ vendor/bin/infection --git-diff-lines

In Process.php line 267:

  The command "'git' 'diff' 'origin/master' '--diff-filter' 'AM' '--name-only' '--' 'src'" failed.

  Exit Code: 127(Command not found)

  Working directory: /my-repo

  Output:
  ================


  Error Output:
  ================
  sh: 1: exec: git: not found

[maks-rafalko]

Thank you for fixing this, makes sense.

I'm not sure what's wrong with GH actions, probably because of retargeting to 0.26? Could you please target to master again? I will enable auto-merge

[sanmai]

There are some required checks for PHP 7.4, we should probably disable in settings.

[maks-rafalko]

There are some required checks for PHP 7.4, we should probably disable in settings.

you are right, branch requirements for 0.* were different in comparison to master. Updated.

Than you @Slamdunk and @sanmai

I will make a release in the following days.

[maks-rafalko]

Released: https://github.com/infection/infection/releases/tag/0.26.14