phase: handle phase with no command flag
Before this changeset, all existing phases have a corresponding flag on the `hg
phase` command. (eg: `hg phase --draft`).
After this changeset, a phase can exists without having an associated flag.
This is useful to introduce a new internal phase that we do not want to expose
to user.
#require symlink
https://bz.mercurial-scm.org/1438
$ hg init
$ ln -s foo link
$ hg add link
$ hg ci -mbad link
$ hg rm link
$ hg ci -mok
$ hg diff -g -r 0:1 > bad.patch
$ hg up 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg import --no-commit bad.patch
applying bad.patch
$ hg status
R link
? bad.patch