fix: Stash pop removes stash from list even when there are conflicts

[wugeer]

This Pull Request fixes/closes #2372 .

It changes the following:

• stash_pop not remove stash from list even when there are conflicts

before change before1005.webm

after change after1005.webm

stash pop success success1005.webm

I followed the checklist:

• [ ] I added unittests
• [x] I ran make check without errors
• [x] I tested the overall application
• [x] I added an appropriate item to the changelog

[wugeer]

@extrawurst Hello, could you please take a moment to review this PR? If the changes aren't good enough, I'll continue working on improving them. :)