Open an editor and edit the text to explain what the branch is
for, to be used by various other commands (e.g. `request-pull`).
---contains <commit>::
- Only list branches which contain the specified commit.
+--contains [<commit>]::
+ Only list branches which contain the specified commit (HEAD
+ if not specified).
--merged [<commit>]::
Only list branches whose tips are reachable from the