pkg-rewrite-absolute.py: use == instead of is for char comparison
Fix warnings when executing the script:
contrib/src/pkg-rewrite-absolute.py:19: SyntaxWarning: "is" with a literal. Did you mean "=="?
if c is '=':
contrib/src/pkg-rewrite-absolute.py:30: SyntaxWarning: "is" with a literal. Did you mean "=="?
elif c is ':':
contrib/src/pkg-rewrite-absolute.py:128: SyntaxWarning: "is" with a literal. Did you mean "=="?
input_file = sys.stdin if args.input is '-' else open(args.input, 'r')
contrib/src/pkg-rewrite-absolute.py:136: SyntaxWarning: "is" with a literal. Did you mean "=="?
output_file = sys.stdout if args.output is '-' else open(args.output, 'w')
Signed-off-by: Marvin Scholz <epirat07@gmail.com>