test_vdrive fails on Solaris

[zooko]

On my GNU/OpenSolaris box ("nooxie"), I usually but not always get this unit test failure:

[FAIL]: allmydata.test.test_system.SystemTest.test_vdrive

Traceback (most recent call last):
  File "/home/zooko/playground/allmydata/tahoe/src/allmydata/test/test_system.py", line 646, in _test_runner
    self.failUnless("size: %d\n" % len(self.data) in output, "%s not in %s" % (len(self.data), output,))
twisted.trial.unittest.FailTest: 112 not in                size: 1500000
       num_segments: 2
       segment_size: 1048578
      needed_shares: 3
       total_shares: 10

         codec_name: crs
       codec_params: 1048578-3-10
  tail_codec_params: 451422-3-10

     plaintext_hash: cqutmpzodq7c7gjdhgh49szcyfnd5mekh4hg6y3ixt4t9yhfsedo
plaintext_root_hash: 7ubp3sz4b6eanbsupiq6msq1ctr6paczxyb7d371afborokjohwy
     crypttext_hash: ixnrjto993xepgu9h39th169rou7zxrjn3sdhusxwfih7bszbexy
crypttext_root_hash: uyezsmdtqooju48s7qfonzsdph4gykn6aui4gtmejoum45dn3z4y
    share_root_hash: f6iccmhg67133akxswcayq57wxb31oy6rjit5cuejjwue4kx745o

Size of data within the share:
               data: 500000
      uri-extension: 436
         validation: 458
Lease #0: owner=0, expire in 2678397s (30 days)

[zooko]

fixed by a18f7aa6d5771d9a

[warner]

and fixed even better by 9b09fd3bf1993233. The problem was that the test depended upon os.walk returning share files in a particular order, and Solaris happened to return them in a different order than the other platforms. The fix was to make sure that we only have one file in the mesh when we run that test (and thus look for those share files), to remove the uncertainty.

Just wanted to make it clear why this appeared to be a solaris-specific problem..