rebase: also include commit of collapsed commits in single transaction When rebase.singletransaction is set, we still used to create a second transaction when committing with --collapse. It's simpler to create a single transaction. Note that in the affected .t file, the test that uses --collapse still appears to create two transactions (it prints "rebase status stored" twice). However, only a single transaction is actually created and the second printout comes from cmdutil.commitforceeditor() that explicitly calls tr.writepending(). Also note the that we now roll back any commits if the user closes the commit message editor with an error code (or leaves the message empty). That might be unfortunate, but it's consistent with how we behave in the --no-collapse case (if the user passed --edit). If we want to change that, I think it should be done consistently in a separate patch. Differential Revision: https://phab.mercurial-scm.org/D2728