py3: add a test to show `hg diff` works on Python 3

py3: implement __bytes__ for committablectx Before this method, calling bytes on workingctx or memctx calls basectx.__bytes__ since the magic method was not defined for this class. When it calls the method from basectx class, it returns TypeError because None is passed into it. After this commit `hg update -C` works on Python 3 if eol is not enabled.

py3: convert exception to bytes to pass into ui.warn() Here encoding.strtolocal() is used because exc maybe an IOError which could contain a valid non-ascii unicode.

py3: convert bool variables to bytes before passing into ui.debug() We can't pass unicodes to ui.debug() and hence we need to convert things to bytes before passing them.

py3: use dict.update() instead of constructing lists and adding them dict.items() returned a list on Python 2 and whereas on Python 3 it returns a view object. So we required a work around. Using dict.update() is better then constructing lists as it should save us on gc churns.

patchbomb: add -B option to select a bookmark Add the -B/--bookmark option to select a bookmark whose changesets and its ancestors will be selected unless a new bookmark/head is found. This is inspired by hg strip -B option.

test: add the mirror push race case for non-contiguous branch head We check case where the raced push update that a head through another named branch while the racing push update that same head.

test: add a push race case where non-contiguous branch head are created We check case where the raced push an update to branch default head while the racing push update that same head but through another named branch.

test: add a push race case where the raced push touch multiple heads We check case where the raced push update all heads while the racing push update one of them.

test: add a push race case where racing push touches multiple heads We check case where the raced push updates a head while the racing push update all of them.