testify shouldn't care if the "wrong" slave returns the result

[bukzor]

This has caused issues twice now.

http://releng.irclogs.yelpcorp.com/2014-04-17.html#829/h829,830,834,835,836,839

[18:36]
<buck> bstack: are you able to get any error messgae from the test runners?
[18:37]
<bstack> ERROR Skipping returning results for test yelp.tests.web.import_servlets_test TestBogusRequest.test_import_cmds_about because of error: Class yelp.tests.web.import_servlets_test TestBogusRequest checked out by runner sandbox_6:1756, not sandbox_21:1757
[18:37]
<bstack> that fantastic error :p ^

http://releng.irclogs.yelpcorp.com/2014-07-15.html#161/h161

[13:08]
<dmitriy> http://buildbot16.yelpcorp.com/builders/sandbox_32/builds/5193/steps/testify%20test/logs/stdio
[13:09]
<buck98> dmitriy: Class yelp.tests.web.assets.js_tests_test TestJsTests_www checked out by runner sandbox_56:5193, not sandbox_32:5193

[bukzor]

This should be only moderately hard to fix, and removes an entire class of failures from testify.

Seeking volunteers.

@astephen2

[rambleraptor]

Yep, I'll look into it.

[bukzor]

Yay, thanks!

[asottile]

Obsolete via #317