localrepo: eliminate local requirements var in init
Localrepo's __init__ function creates a local requirements set to add to before
it replaces the instance's set with it. This is unnecessary, so let's just
use the instance's set directly.
localrepo: rename requirements parameter in stream_in()
To avoid confusion from overloading of the variable name "requirements", the
requirements is renamed to remotereqs for localrepo's stream_in() function.