Steps to reproduce:

• open a project having a git repository
• invoke Tools -> Git -> Actions on Commits...
• click 'Browse History...'
• double click a change that is listed below a merge
• dialog shows a change (HEAD~X with X a number) that does not fit the selected change as a git merge seem to make the HEAD~X syntax useless (might be better to just use the sha that is listed for the change already inside the selection dialog)