phabricator: avoid a stacktrace when command arguments are missing Previously, the TypeError wasn't properly converted to a SignatureError when improper arguments were supplied to the inner function, because the stack depth is 2 inside the vcrcommand decorator. The `__name__` and `__doc__` attributes need to be reassigned to the new wrapper so that the help summary is available. Differential Revision: https://phab.mercurial-scm.org/D8209