$ rm -fr TestingPersonalCondor
 {endcode}
 After either of these, you can re-run the tests as above.
+
+{subsection: Cached Externals}
+
+Builds by default cache the externals in /scratch/condor-externals. If you're sharing the machine with others, you may collide and have problems.  Solution, add
+{code}
+-DSCRATCH_STAGE:PATH=/path/to/a/private/directory
+{endcode}
+to your invocation of configure_uw