Repair Translation Check

[mstv]

The translation check has regressed again: fails, if the master has newer translations.

STR:

• PR with translation change
• concurrent merge with translation change to master
• build PR

[RussKie]

I'll have a look

[RussKie]

Got a repro f5c663c

Here's what's happening:

1. The master has a changed translation, when we perform a soft reset the index it contains xlf files:
   
2. Then we build and run the loc check, which detects the changed xlf

In 3.5 branch we would

1. Reset
2. Build
3. Undo reset
4. Run loc check

[mstv]

I think you should have a look at the code removed (again) from appveyor.yml in 3eea466 or at 8da72f4.
It did/does only work this way.

[RussKie]

Tested in https://ci.appveyor.com/project/gitextensions/gitextensions/builds/39945061