Using Raise=True was only papering over the real problem in the nested
command error handling. The actual issue is that we were trying to
return an IrcMsg from NestedCommandsIrcProxy.__init__. Dropping
Raise=True and moving return to its own line is the correct fix and
resolves the test failure in testMaximumNestingDepth.
This commit reverts 7838cae3bc5f23c271c8baba0630d6969d8f1b55
Signed-off-by: James McCoy <vega.james@gmail.com>