Whoops, redo-oob was slightly wrong when used with -j.

We called 'redo' instead of 'redo-ifchange' on our indeterminate objects.
Since other instances of redo-oob might be running at the same time, this
could cause the same object to get rebuilt more than once unnecessarily.
The unit tests caught this, I just didn't notice earlier.

builder.py

@@ -73,7 +73,7 @@ class BuildJob:
         except ImmediateReturn, e:
             return self._after2(e.rv)
 
-        if dirty == True:
+        if vars.NO_OOB or dirty == True:
             self._start_do()
         else:
             self._start_oob(dirty)