test suite failure rend_cache/store_v2_desc_as_client

I had this fail on 0.2.8.3 on wheezy armel.

..
rend_cache/failure_remove: OK
rend_cache/intro_failure_note: OK
rend_cache/lookup: OK
rend_cache/lookup_v2_desc_as_dir: OK
rend_cache/store_v2_desc_as_client: 
  FAIL ../src/test/test_rendcache.c:201: assert(ret OP_EQ -1): 0 vs -1
  [store_v2_desc_as_client FAILED]
rend_cache/store_v2_desc_as_client_with_different_time: OK
rend_cache/store_v2_desc_as_dir: OK
..
1/716 TESTS FAILED. (1 skipped)