tests: teach get-with-headers.py some new tricks
We add the ability to specify arbitrary HTTP request headers and
to save the HTTP response body to a file. These will be used in
upcoming commits.
Differential Revision: https://phab.mercurial-scm.org/D1921
To run the tests, do:
cd tests/
python run-tests.py
See https://mercurial-scm.org/wiki/WritingTests for
more information on writing tests.