Work around py test_runner issue with ns packages.

Review Request #1813 - Created Feb. 21, 2015 and submitted

John Sirois
1147, 1149, 1151
benjyw, dturner-tw, patricklaw
The python test_runner does not handle running tests from seperate
source trees contributinng to the same _test_ ns package.  We'd like to
run all contrib/ tests together and these all share the
`pants_test/contrib` ns package, so this test_runner bug forces us to
use the runner in `--no-fast` mode, ie: run each test target in its own
chroot / py.test session.

 build-support/bin/ | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
CI went green here:

I also tested this on Dominic's PR @ which was failing in the
contrib ci test shard prior to the fix.
John Sirois
Mateo Rodriguez
Eric Ayers
John Sirois
David Turner
John Sirois
John Sirois
Review request changed

Status: Closed (submitted)

Patrick Lawson
Ship It!