[FIX] runbot_merge: access to self in loop

This is a low issue as the prs of a commit are only listed from the
form so the compute is pretty much always called with a single record,
but still an unforced error which can easily be fixed.

runbot_merge/models/pull_requests.py

@@ -1810,7 +1810,7 @@ class Commit(models.Model):
     def _compute_prs(self):
         for c in self:
             c.pull_requests = self.env['runbot_merge.pull_requests'].search([
-                ('head', '=', self.sha),
+                ('head', '=', c.sha),
             ])