--- a/mercurial/lock.py	Thu Sep 24 22:00:51 2015 -0700
+++ b/mercurial/lock.py	Thu Sep 24 22:07:55 2015 -0700
@@ -102,7 +102,16 @@
                 self.held = 1
             except (OSError, IOError) as why:
                 if why.errno == errno.EEXIST:
-                    locker = self.testlock()
+                    locker = self._readlock()
+                    # special case where a parent process holds the lock -- this
+                    # is different from the pid being different because we do
+                    # want the unlock and postrelease functions to be called,
+                    # but the lockfile to not be removed.
+                    if locker == self.parentlock:
+                        self._parentheld = True
+                        self.held = 1
+                        return
+                    locker = self._testlock(locker)
                     if locker is not None:
                         raise error.LockHeld(errno.EAGAIN,
                                              self.vfs.join(self.f), self.desc,