Removing a fuzzy string in the repository is undone during the next sync

[eemeli]

This might be a regression from #3312, or it might already be the case that if a .po file in a repository is manually edited so that a string with a #, fuzzy flag has that flag removed and the msgstr value set to an empty string "", a subsequent Pontoon sync will re-write the string in the repository with the fuzzy value and flag.

If the msgstr value is set to a non-empty value, then that's handled correctly by Pontoon sync. Rejecting a fuzzy translation in Pontoon is handled correctly by sync.

The error case here is probably really rare.