cmdutil: stop tryimportone from using dirstateguard (BC)
There is no user of 'cmdutil.tryimportone()' other than
'commands.import_()', which can restore dirstate at failure of
applying patches by transaction or dirstateguard.
Therefore, it is reasonable to stop 'tryimportone()' from using
redundant 'dirstateguard', even though it changes behavior of
'tryimportone()'.
After this patch, 3rd party extensions should use 'dirstateguard' or
so explicitly, if they want to restore dirstate at failure of
importing a patch.
running: init test1
result: None
running: add foo
result: 0
running: commit -m commit1 -d 2000-01-01 foo
result: None
running: commit -m commit2 -d 2000-01-02 foo
result: None
running: log -r 0
changeset: 0:0e4634943879
user: test
date: Sat Jan 01 00:00:00 2000 +0000
summary: commit1
result: None
running: log -r tip
changeset: 1:45589e459b2e
tag: tip
user: test
date: Sun Jan 02 00:00:00 2000 +0000
summary: commit2
result: None