merge: make calculateupdates() return file->action dict
This simplifies largefiles' overridecalculateupdates(), which no
longer has to do the conversion it started doing in
38e55e55ae4d
(largefiles: rewrite merge code using dictionary with entry per file,
2014-12-09).
To keep this patch small, we'll leave the name 'actionbyfile' in
overrides.py. It will be renamed in the next patch.
http://mercurial.selenic.com/bts/issue1089
$ hg init
$ mkdir a
$ echo a > a/b
$ hg ci -Am m
adding a/b
$ hg rm a
removing a/b (glob)
$ hg ci -m m a
$ mkdir a b
$ echo a > a/b
$ hg ci -Am m
adding a/b
$ hg rm a
removing a/b (glob)
$ cd b
Relative delete:
$ hg ci -m m ../a
$ cd ..