rcutil: don't check if defaultrc/ is a directory -- we know it is
`mercurial/defaultrc/` is a directory both in the Mercurial repo and
once installed on a target platform. The directory was created in
c4ce077588d0 (config: introduce "built-in" default configuration
settings in default.d, 2014-09-04). That commit has some more
information, but it still doesn't seem to say that `defaultrc/` (then
called `default.d/`) could be a file. Perhaps the check was there to
allow you to run the same code on an older install/repo?
Differential Revision: https://phab.mercurial-scm.org/D7624
https://bz.mercurial-scm.org/619
$ hg init
$ echo a > a
$ hg ci -Ama
adding a
$ echo b > b
$ hg branch b
marked working directory as branch b
(branches are permanent and global, did you want a bookmark?)
$ hg ci -Amb
adding b
$ hg co -C 0
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
Fast-forward:
$ hg merge b
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg ci -Ammerge
Bogus fast-forward should fail:
$ hg merge b
abort: merging with a working directory ancestor has no effect
[255]
Even with strange revset (issue4465)
$ hg merge ::.
abort: merging with a working directory ancestor has no effect
[255]