When updating to lose an external, the code should handle a locally missing externals item, and it does. Add a test for this in an existing test case.
When updating to lose an external, the code should handle a locally missing
externals item, and it does. Add a test for this in an existing test case.

* subversion/tests/cmdline/externals_tests.py
  (update_lose_external): Remove one externals wc dir.

Patch by: Daniel Näslund <daniel@longitudo.com>

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion