download: support -x when cherry-picking

This is a pretty common option for people to want too use, so include
it as a pass-thru option when cherry-picking.

Bug: https://crbug.com/gerrit/9418
Change-Id: I2a24c1ed7544541719caa4d3c0574347a151a1b0
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/259853
Reviewed-by: David Pursehouse <dpursehouse@collab.net>
Tested-by: Mike Frysinger <vapier@google.com>
diff --git a/project.py b/project.py
index a58af4f..d35ad52 100644
--- a/project.py
+++ b/project.py
@@ -2681,10 +2681,12 @@
       if self._allrefs:
         raise GitError('%s checkout %s ' % (self.name, rev))
 
-  def _CherryPick(self, rev, ffonly=False):
+  def _CherryPick(self, rev, ffonly=False, record_origin=False):
     cmd = ['cherry-pick']
     if ffonly:
       cmd.append('--ff')
+    if record_origin:
+      cmd.append('-x')
     cmd.append(rev)
     cmd.append('--')
     if GitCommand(self, cmd).Wait() != 0: