Use index-based stash references

[marcelltoth]

Fixes #1267

Following the discussion in #1267 I'm making this PR here to make the suggested change. Please see the issue for more details.

This also means we can remove the MSYS workaround, and the corresponding test.

[iiroj]

Thanks for the PR! I think a good commit message would be fix: use index-based stash references for improved MSYS2 compatibility, but I can reword it when merging.

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change

Comparison is base (0d843ce) 100.00% compared to head (da82500) 100.00%.

Additional details and impacted files

@@            Coverage Diff            @@
##            master     #1270   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           26        26           
  Lines          735       733    -2     
  Branches       198       197    -1     
=========================================
- Hits           735       733    -2     

Impacted Files	Coverage Δ
lib/gitWorkflow.js	100.00% <100.00%> (ø)

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[marcelltoth]

Thanks for merging! And sorry I had not realized you're using semantic PR titles here, I'll adapt to that for future PRs

[iiroj]

This will be published to npm when #1272 is merged, because of some semantic-release issues.