update: warn about other topological heads on bare update A concern around the user experience of Mercurial is user getting stuck on there own topological branch forever. For example, someone pulling another topological branch, missing that message in pull asking them to merge and getting stuck on there own local branch. The current way to "address" this concern was for bare 'hg update' to target the tipmost (also latest pulled) changesets and complain when the update was not linear. That way, failure to merge newly pulled changesets would result in some kind of failure. Yet the failure was quite obscure, not working in all cases (eg: commit right after pull) and the behavior was very impractical in the common case (eg: issue4673). To be able to change that behavior, we need to provide other ways to alert a user stucks on one of many topological head. We do so with an extra message after bare update: 1 other heads for branch "default" Bookmark get its own special version: 1 other divergent bookmarks for "foobar" There is significant room to improve the message itself, and we should augment it with hint about how to see theses other heads or handle the situation (see in-line comment). But having "a" message is already a significant improvement compared to the existing situation. Once we have it we can iterate on a better version of it. As having such message is an important step toward changing the default destination for update and other nicety, I would like to move forward quickly on getting such message. This was discussed during London - October 2015 Sprint.

tests: mock getpid to reduce glob usage With util.getpid, it is now possible to define fixed pids. Future iterations can define a map of pids on a locked first come first serve basis to create a more realistic harness, but for now this is good enough. This applies to blackbox, but could apply to other tests as well.

util: enable getpid to be replaced This will enable tests to write stable process ids.

blackbox: refactor use of vfs as _bbvfs

blackbox: flush output file descriptor Without this, when there are multiple ui views, each blackbox will have its own file handle, and the logging will be in a really bad order. Also, because of the way blackbox works, it never closes its file handles, which means the last output before exit is often lost.

tests: change blackbox test to work cross platform While it is not easy to make a file 000 on Windows, you can emulate most of the behaviors by replacing the file with a directory. Also corrects test description to properly indicate that failing to read from the log is fatal.

merge: document checkignored and checkunknown configs again These options were undocumented for 3.7 because of an issue found during the freeze (see rev 7cb7264cfd52). This issue has now been fixed, so we can document these options again.

rebase: respect checkunknown and checkignored in more cases checkunknown and checkignored are currently respected for updates and regular merges, but not for certain kinds of rebases. To be precise, they aren't respected for rebases when: (1) we're rebasing while currently on the destination commit, and (2) an untracked or ignored file F is currently in the working copy, and (3) the same file F is in a source commit, and (4) F has different contents in the source commit. This happens because rebases set force to True when calling merge.update. Setting force to True makes a lot of sense in general, but it turns out the force option is overloaded: there's a deprecated '--force' option in merge that allows you to merge in outstanding changes, including changes in untracked files. We use the 'mergeforce' parameter to tell those two cases apart. I think the behavior during rebases when checkunknown is 'abort' (the default) is wrong -- we should abort on or overwrite differing untracked files, not try to merge them in. However that currently breaks rebases by aborting in the middle -- we need better handling for that case before we can change the default.

test-merge-force: add tests for merge.checkunknown=warn In an upcoming patch we're going to change the behavior of some merges with merge.checkunknown=warn or ignore -- ensure that the behavior of the deprecated 'merge --force' remains the same.

merge: tell _checkunknownfiles about whether this was merge --force In an upcoming patch we'll have different behavior here for when 'merge --force' is used as opposed to when other kinds of force operations are performed, like rebases.