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'.

largefiles: check hash of files in the store before copying to working dir If the store somehow got corrupted, users could end up in weird situations that were very hard to recover from or lead to propagation of the corruption. Instead, spend the extra time checking the hash when copying to the working directory. If it doesn't match, emit a warning, and don't put wrong content in the working directory.

largefiles: test coverage of handling of store corruption This reveals that update might put a corrupted largefile in the working directory where it will show up as modified and ready for commit.