/srv/leap/bin/run_tests should return error code 1 on failures when checking a single test

when i run all tests, the script returns exit code 1 on error like it should:

root@couch1:/srv/leap/tests/white-box# /srv/leap/bin/run_tests
PASS: Network > Can connect to internet
PASS: Network > Stunnel is running
PASS: Couchdb > Daemons running
PASS: Couchdb > Couch is working
PASS: Couchdb > Nodes are in replication database
WARN: Couchdb > Replica membership is kosher:
  These nodes are configured but not available:
  bigcouch@couch2.bitmask.net
PASS: Couchdb > Acl users exist
FAIL: Couchdb > Required databases exist [couchdb.rb:83]:
  Expected a 200 status code from http://admin:password@localhost:5984/identities, but got 500 instead.
Tests halted on failure (because of --no-continue).
root@couch1:/srv/leap/tests/white-box# echo $?
1

but when i run a single test it returns 0 even when the test fails:

root@couch1:/srv/leap/tests/white-box# /srv/leap/bin/run_tests --test TestCouchdb/replica_membership_is_kosher
WARN: Couchdb > Replica membership is kosher:
  These nodes are configured but not available:
  bigcouch@couch2.bitmask.net
1 tests, 0 assertions, 0 passes, 0 failures, 0 errors, 0 skips
root@couch1:/srv/leap/tests/white-box# echo $?
0

i want to use these tests for a script that waits for successful clustering, so i don't need to reinvent the wheel (#5269 (closed)).

(from redmine: created on 2014-04-04, closed on 2014-04-17, relates #5269 (closed), relates #5519 (closed))