bundle2: attribute remote failures to remote (issue4788) Before bundle2, hook output from hook failures was prefixed with "remote: ". Up to this point with bundle2, the output was converted to the message to print in an Abort exception. This had 2 implications: 1) It was unclear whether an error message came from the local repo or the remote 2) The exit code changed from 1 to 255 This patch changes the handling of error:abort bundle2 parts during push to prefix the error message with "remote: ". This restores the old behavior. We still preserve the behavior of raising an Abort during bundle2 application failure. This is a regression from pre-bundle2 because the exit code changed. Because we no longer raise an Abort with the remote's message, we needed to insert a message for the new Abort. So, I invented a new error message for that. This is another change from pre-bundle2. However, I like the new error message because it states unambiguously who aborted the push failed, which I think is important for users so they can decide what's next.

tests: add tests for remote hook output (issue4788) The added tests don't agree in their output. This demonstrates a difference in `hg push` behavior between pre-bundle2 and bundle2. A subsequent patch will attempt to restore some of the pre-bundle2 behavior to bundle2.

help: mention alias and revsetalias in description of HGPLAINEXCEPT

debugrevlog: cope with empty revlog files I have no idea where it came from, but my clone of Mercurial has an empty filelog for `contrib/hgfixes/__init__.py` - it's *valid*, just contains no nodes. Without this change, debugrevlog crashes with a zero division error.

largefiles: don't mute and obfuscate http errors when putlfile fails 'unexpected putlfile response: None' when an http error occurs is not very helpful. Instead, leave the handling of urllib2.HTTPError exceptions to other layers.

largefiles: test coverage of error handling from putlfile This reveals a wrong and unhelpful 'unexpected putlfile response'.