subrepo: make update -C clean the working directory for svn subrepos
This makes 'hg update --clean' behave the same way for both kinds of
subrepositories. Before Subversion subrepos did not take the clean
parameter into account, but just updated to the given revision and
merged uncommitted changes into that.
$ hg init rep
$ cd rep
$ mkdir dir
$ touch foo dir/bar
$ hg -v addremove
adding dir/bar
adding foo
$ hg -v commit -m "add 1"
dir/bar
foo
committed changeset 0:6f7f953567a2
$ cd dir/
$ touch ../foo_2 bar_2
$ hg -v addremove
adding dir/bar_2
adding foo_2
$ hg -v commit -m "add 2"
dir/bar_2
foo_2
committed changeset 1:e65414bf35c5
$ cd ..
$ hg init sim
$ cd sim
$ echo a > a
$ echo a >> a
$ echo a >> a
$ echo c > c
$ hg commit -Ama
adding a
adding c
$ mv a b
$ rm c
$ echo d > d
$ hg addremove -n -s 50 # issue 1696
removing a
adding b
removing c
adding d
recording removal of a as rename to b (100% similar)
$ hg addremove -s 50
removing a
adding b
removing c
adding d
recording removal of a as rename to b (100% similar)
$ hg commit -mb