Also clean up test_scripts.PregeneratedCode:
* fetch results from both sides at the same time
* only check rc when using a subprocess, since the direct call doesn't
use rc=0 anymore
* no need to cancel the other side's Deferred when one errors
* provide more information if stderr was non-empty
When test_scripts ran two clients at the same time, an error in one
could leave the other hanging (in a thread). One Deferred would errback,
the other would hang. Tests wait on one Deferred at a time, so if we're
unlucky and were waiting on the hanging Deferred (instead of the
erroring one), we'll wait forever, or at least until the default test
timeout of 180 seconds.
This adds an errback to notice when either client has errored, and
cancels the other Deferred, so it doesn't matter which one we wait upon
first.
Some tests failed to override --transit-helper, which meant they
intermittently talked to the real transit server (briefly, before
deciding the local+direct connection was better).
This requires a DB delete/recreate when upgrading. It changes the server
protocol, and app IDs, so clients cannot interoperate with each other
across this change, nor with the server. Flag day for everyone!
Now apps do not share channel IDs, so a lot of usage of app1 will not
cause the wormhole codes for app2 to get longer.
* declare transit records and handshake keys are bytes, not str
* declare transit connection hints to be str
* use six.moves.socketserver, six.moves.input for Verifier query
* argparse "--version" writes to stderr on py2, stdout on py3
* avoid xrange(), use subprocess.Popen(universal_newlines=True)
