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.