environmentfrombatchfile: Fix some warnings reported by pylint

 W: 60,12:consume: Redefining built-in 'iter'
 C: 62,20:consume: More than one statement on a single line
 C: 98,4:get: Comma not followed by a space
    pairs = (line.rstrip().split('=',1) for line in lines)
                                    ^^
 W: 96,4:get: Unused variable 'handle_line'

Change-Id: I49a6742c0ad1b4c5699c454329ff95388efcdc52
Reviewed-by: Iikka Eklund <iikka.eklund@digia.com>