subrepo: handle svn tracked/unknown directory collisions stable

subrepo: handle svn tracked/unknown directory collisions

This happens more often than expected. Say you have an svn subrepository with
python code. Python would have generated unknown .pyc files. Now, you rebase
this setup on a revision where a directory containing python code does not
exist. Subversion is first asked to remove this directory when updating, but
will not because it contains untracked items. Then it will have to bring back
the directory after the merge but will fail because it now collides with an
untracked directory.

Using --force is not very elegant but it is much simpler than rewriting our own
purge command for subversion.

--- a/mercurial/subrepo.py	Wed Mar 02 21:57:20 2011 -0600
+++ b/mercurial/subrepo.py	Fri Mar 04 14:00:49 2011 +0100
@@ -625,7 +625,8 @@
     def get(self, state, overwrite=False):
         if overwrite:
             self._svncommand(['revert', '--recursive'])
-        status = self._svncommand(['checkout', state[0], '--revision', state[1]])
+        status = self._svncommand(['checkout', '--force', state[0],
+                                   '--revision', state[1]])
         if not re.search('Checked out revision [0-9]+.', status):
             raise util.Abort(status.splitlines()[-1])
         self._ui.status(status)

--- a/tests/test-subrepo-svn.t	Wed Mar 02 21:57:20 2011 -0600
+++ b/tests/test-subrepo-svn.t	Fri Mar 04 14:00:49 2011 +0100
@@ -438,3 +438,60 @@
   $ svnversion
   2
   $ cd ..
+
+Test case where subversion would fail to update the subrepo because there
+are unknown directories being replaced by tracked ones (happens with rebase).
+
+  $ cd $WCROOT/src
+  $ mkdir dir
+  $ echo epsilon.py > dir/epsilon.py
+  $ svn add dir
+  A         dir
+  A         dir/epsilon.py
+  $ svn ci -m 'Add dir/epsilon.py'
+  Adding         src/dir
+  Adding         src/dir/epsilon.py
+  Transmitting file data .
+  Committed revision 6.
+  $ cd ../..
+  $ hg init rebaserepo
+  $ cd rebaserepo
+  $ svn co -r5 --quiet "$SVNREPO"/src s
+  $ echo "s =        [svn]       $SVNREPO/src" >> .hgsub
+  $ hg add .hgsub
+  $ hg ci -m addsub
+  committing subrepository s
+  $ echo a > a
+  $ hg ci -Am adda
+  adding a
+  $ hg up 0
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  $ svn up -r6 s
+  A    s/dir
+  A    s/dir/epsilon.py
+  
+  Fetching external item into 's/externals'
+  Updated external to revision 1.
+  
+  Updated to revision 6.
+  $ hg ci -m updatesub
+  committing subrepository s
+  created new head
+  $ echo pyc > s/dir/epsilon.pyc
+  $ hg up 1
+  D    $TESTTMP/rebaserepo/s/dir
+  
+  Fetching external item into '$TESTTMP/rebaserepo/s/externals'
+  Checked out external at revision 1.
+  
+  Checked out revision 5.
+  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg up 2
+  E    $TESTTMP/rebaserepo/s/dir
+  A    $TESTTMP/rebaserepo/s/dir/epsilon.py
+  
+  Fetching external item into '$TESTTMP/rebaserepo/s/externals'
+  Checked out external at revision 1.
+  
+  Checked out revision 6.
+  1 files updated, 0 files merged, 1 files removed, 0 files unresolved