bundle2: support a "version" argument in `changegroup` part When included, this mandatory parameter (mandatory == cannot be ignored) lets the part handler select the right cgunpacker class.

bundle2caps: advertise the available versions for changegroup packer This will let the bundle2 client and server detect what packer they should be using. This detection part is not done. I expect it to be done with the addition of the second packer (with generaldelta support).

changegroup: add a "packermap" dictionary to track different packer versions We only have "01" right now, but we should get general delta in soon. Bundle2 is expected to make use of this to advertise and select the right packer to use on both sides.

templater: don't overwrite the keyword mapping in runsymbol() (issue4362) This keyword remapping was introduced in e06e9fd2d99f as part of converting generator based iterators into list based iterators, mentioning "undesired behavior in template" when a generator is exhausted, but doesn't say what and introduces no tests. The problem with the remapping was that it corrupted the output for keywords like 'extras', 'file_copies' and 'file_copies_switch' in templates such as: $ hg log -r 142b5d5ec9cc --template "{file_copies % ' File: {file_copy}\n'}" File: mercurial/changelog.py (mercurial/hg.py) File: mercurial/changelog.py (mercurial/hg.py) File: mercurial/changelog.py (mercurial/hg.py) File: mercurial/changelog.py (mercurial/hg.py) File: mercurial/changelog.py (mercurial/hg.py) File: mercurial/changelog.py (mercurial/hg.py) File: mercurial/changelog.py (mercurial/hg.py) File: mercurial/changelog.py (mercurial/hg.py) What was happening was that in the first call to runtemplate() inside runmap(), 'lm' mapped the keyword (e.g. file_copies) to the appropriate showxxx() method. On each subsequent call to runtemplate() in that loop however, the keyword was mapped to a list of the first item's pieces, e.g.: 'file_copy': ['mercurial/changelog.py', ' (', 'mercurial/hg.py', ')'] Therefore, the dict for the second and any subsequent items were not processed through the corresponding showxxx() method, and the first item's data was reused. The 'extras' keyword regressed in de7e6c489412, and 'file_copies' regressed in 0b241d7a8c62 for other reasons. The common thread of things fixed by this seems to be when a list of dicts are passed to the templatekw._hybrid class.