Bid merge is a new rarely used feature that the user explicitly enabled - we
should tell/warn when the user actually is using it, just like we tell when we
not are using it.
Give a message like
note: merging 3b08d01b0ab5+ and adfe50279922 using bids from ancestors 0f6b37dbe527 and 40663881a6dd
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.
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 f19507e1bcf2).
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.
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.
