Log hashes of local branches when deleting them

[stefanhaller]

This makes it easier to recover them if they were deleted accidentally.

We only do this for local branches for now, we don't bother for remote branches; it would be trickier there, because the branch on the server might not actually point to the same hash as our local remote tracking branch does.

Fixes #2468.

[codacy-production]

Coverage summary from Codacy

See diff coverage on Codacy

Coverage variation	Diff coverage
Report missing for 050bffa1	✅ 100.00%

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (050bffa)	Report Missing	Report Missing	Report Missing
Head commit (8ccdfb8)	61070	53502	87.61%

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#5441)	20	20	100.00%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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Footnotes

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