The _build_revision method in Hg class gets called with the wrong number
of arguments. This tiny patch adds a 5th argument to the method
declaration to prevent python from throwing an exception.

(Bitbake rev: 623e9c7f7a9cf12b8c81c26cc608990682a601dd)

Signed-off-by: Julian Pidancet <julian.pidancet@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>