rebase: reduce scope of try catch in restorestate Refactoring by reduce the scope of the try catch block so that it only captures what it needs. I could have made it smaller but another patch in the series will add onto it.

rebase: on abort delete rebase state file no matter what When a user's repository is in an unfinished rebase state and they choose to abort, at a minimum, the repo should be out of that state. We've found situations where the user could not leave the state unless manually deleting the rebasestate file. This fix ensures that no matter what exception may be raised during the abort, the rebase state file will be deleted, the user will be out of the rebase state and they can get their repository into a workable condition.

contrib: make editmerge look for merge markers at the beginning of the line This fix adds a caret to the start of the regex looking for merge markers. This avoids the issue arises when you've real merge conflicts in a file that tests for the existance of merge markers in test output. Editmerge will not open on the fake/tested merge markers because they'll be indented in.

commit: abort when a committemplate is not changed If a committemplate is provided and no message is provided on the command line, and no edits are made to the commit template, then abort the commit.

localrepo.commit: disallow commit when driver-resolved files exist This code will not currently be activated because there's no code to mark files as driver-resolved in core. This point is also somewhat hard to plug into from extensions.

merge.mergestate: add a generator for driver-resolved files Just like for unresolved files above, we need to be able to tell what files are driver-resolved.

hook: for python hooks, also return whether an exception was raised The hook code treats python hooks raising an exception and returning True as the exact same. This is OK for hooks themselves, but other code that wants to invoke external code using the same underlying code is a bit more interested in making a distinction.

hook.runhooks: return a dict of result values This will be useful to other calling code that would be interested in what the individual hooks return.

hook: factor out determination of hooks from running them This will allow other code to run a predetermined series of hooks.

mq: generate patch names from first line of description Avoid the pointless numeric rev.diff patch names. Instead, do like mbox extension does and create meaningful patch names.