rebase: also test abort from pretxnclose error Different hooks will have different properties so we cover more hooks to catch further regressions.

rebase: reinforce testing around precommit hook interrupting a rebase Different hooks will have different properties so we cover more hooks to catch further regression.

rebase: provides test case for (issue5610) The 4.2 release introduces a regression regarding the behavior of rebase with some hook failures. We add the tests from the bug report from Henrik Stuart to our test base to prevent further regression on this.

rebase: backed out changeset cf8ad0e6c0e4 (issue5610) Having a single transaction for rebase means the whole transaction gets rolled back on error. To work around this a small hack has been added to detect merge conflict and commit the work done so far before exiting. This hack works because there is nothing transaction related going on during the merge phase. However, if a hook blocks the rebase to create a changeset, it is too late to commit the work done in the transaction before the problematic changeset was created. This leads to the whole rebase so far being rolled back. Losing merge resolution and other work in the process. (note: rebase state will be fully lost too). Since issue5610 is a pretty serious regression and the next stable release is a couple day away, we are taking the backout route until we can figure out something better to do.

rebase: backed out changeset 2519994d25ca In the process of fixing issue5610 in 4.2.2, we are trying to backout cf8ad0e6c0e4. This changeset is making changes that depend on cf8ad0e6c0e4, so we need to back it out first. Since issue5610 is pretty serious regression and the next stable release is a couple of days away, we are taking the backout route until we can figure out something better to do.

make: add Debian 9 (Stretch) docker target

make: templatize Debian build target a la e63dfbbdbd07