wireproto: don't compress errors from getbundle() Errors should be small. There's no real need to compress them. Truth be told, there's no good reason to not compress them either. But leaving them uncompressed makes it easier to test failures by looking at the raw HTTP response. This makes it easier for us to write tests. It may make it easier for people writing their own clients. Differential Revision: https://phab.mercurial-scm.org/D1922

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