merge: change priority / ordering of merge actions
The ordering of actions matters. Normal file system semantics is that files
have to be removed before a directory with the same name can be created.
Before the first ordering key was to have 'r' and 'f' actions come first,
secondary key was the filename.
Because of future refactorings we want to consistently have all action types
(with a sensible priority) as separate first keys. Grouped by action type, we
sort by filename.
Not processing in strict filename order could give worse performance,
especially on spinning disks. That is however primarily an issue in the cases
where "all" actions are of the same kind and will be grouped together anyway.
$ rm -rf a
$ hg init a
$ cd a
$ echo a > a
$ hg ci -Am0
adding a
$ hg tag t1 # 1
$ hg tag --remove t1 # 2
$ hg co 1
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg tag -f -r0 t1
$ hg tags
tip 3:a49829c4fc11
t1 0:f7b1eb17ad24
$ cd ..