diff -Nur plague-0.4.4.1-orig/builder/builder.py plague-0.4.4.1/builder/builder.py
--- plague-0.4.4.1-orig/builder/builder.py	2006-03-13 16:09:23.000000000 +0100
+++ plague-0.4.4.1/builder/builder.py	2007-09-19 02:53:00.000000000 +0200
@@ -370,11 +370,17 @@
             self._start_cleanup()
 
     def _status_prepping(self):
+        # Refresh mock status to see whether it changed during sleep.
+        # Avoid mock/plague race condition.
+        if not self._mock_is_prepping():
+            if not self._mock_using_repo():  # status changed during sleep
+                self._status = 'building'
+            return
         # Mock shouldn't exit at all during the prepping stage, if it does
         # something is wrong
         self._watch_mock('failed', 'failed')
         if self._status != 'prepping':
-               return
+            return
 
         # We need to make sure that mock has dumped the status file withing a certain
         # amount of time, otherwise we can't tell what it's doing
@@ -388,8 +394,6 @@
         else:
             if not self._mock_config and self._mock_is_prepping():
                 self._mock_config = self._read_mock_config()
-            if not self._mock_using_repo():
-                self._status = 'building'
 
     def _status_building(self):
         self._watch_mock('done', 'failed')