merge: with merge.preferancestor=*, run an auction with bids from ancestors
The basic idea is to do the merge planning with all the available ancestors,
consider the resulting actions as "bids", make an "auction" and
automatically pick the most favourable action for each file.
This implements the basic functionality and will only consider "keep" and
"get" actions. The heuristics for picking the best action can be tweaked later
on.
By default it will only pass ctx.ancestor as the single ancestor to
calculateupdates. The code path for merging with a single ancestor is not
changed.
log: changed implementation to use graphlog code
Now that revsets work in a lazy way, log code can be changed to parse every
option into a revset and then evaluate it lazily.
Now expressions like
"hg log -b default -b ."
are converted into a revset using the same code as graphlog.
context: introduce merge.preferancestor for controlling which ancestor to pick
Multiple revisions can be specified in merge.preferancestor, separated by
whitespace. First match wins.
This makes it possible to overrule the default of picking the common ancestor
with the lowest hash value among the "best" (introduced in
3605d4e7e618).
This can for instance help with some merges where the 'wrong' ancestor is used.
There will thus be some overlap between this and the problems that can be
solved with a future 'consensus merge'.
Mercurial will show a note like
note: using
40663881a6dd as ancestor of
3b08d01b0ab5 and
adfe50279922
alternatively, use --config merge.preferancestor=
0f6b37dbe527
when the option is available, listing all the alternative ancestors.
context: tell when .ancestor picks one of multiple common ancestors heads
Show a message like
note: using
0f6b37dbe527 as ancestor of
adfe50279922 and
cf89f02107e5
So far this is just a warning - there is nothing the user can do to select
another ancestor.