hgweb: prevent triggering dummy href="#" handler Follow up for the previous patch.

paper: add href="#" to links with click handlers This restores the styling that was accidentally removed by the previous change to these files. Differential Revision: https://phab.mercurial-scm.org/D3438

paper: don't register click handlers with inline javascript (issue5812) The use of inline href="javascript:" undermines CSP policies that don't allow inline javascript. This commit changes the registering of the diffstat and line wrapping toggle handlers to the the global DOMContentLoaded handler, thus eliminating all inline javascript from the paper template. Differential Revision: https://phab.mercurial-scm.org/D3437

hgweb: allow Content-Security-Policy header on 304 responses (issue5844) A side-effect of 98baf8dea553 was that the Content-Security-Policy header was set on all HTTP responses by default. This header wasn't in our list of allowed headers for HTTP 304 responses. This would trigger a ProgrammingError when a 304 response was issued via hgwebdir. This commit adds Content-Security-Policy to the allow list of headers for 304 responses so we no longer encounter the error. Differential Revision: https://phab.mercurial-scm.org/D3436

hgweb: discard Content-Type header for 304 responses (issue5844) A side-effect of 98baf8dea553 was that hgwebdir always sets a global default for the Content-Type header. HTTP 304 responses don't allow the Content-Type header. So a side-effect of this change was that HTTP 304 responses served via hgwebdir resulted in a ProgrammingError being raised. This commit teaches our 304 response issuing code to drop the Content-Type header. Differential Revision: https://phab.mercurial-scm.org/D3435

tests: add tests demonstrating ISE for HTTP 304 responses with hgwebdir There are two separate failures here. One for the Content-Type header. Another for the Content-Security-Policy header. Differential Revision: https://phab.mercurial-scm.org/D3434

hgweb: guard against empty Content-Length header Discussion in issue 5860 seems to indicate this can occur. Differential Revision: https://phab.mercurial-scm.org/D3432

test-push-http: do not clear pid file It's okay now, but we'll end up leaking daemon processes if we add some more.

debugcolor: fix crash by empty styles (issue5856)

tests: explicitly define compression engines for tests The zstd compression engine requires C extensions and isn't present in pure Python builds. The compression engine list leaks into the server capabilities string. Unless we're testing functionality specific to a compression format, the set of compression formats supported by a server doesn't matter much. So this commit explicitly defines the server's compression engines for some tests so behavior is consistent between pure and non-pure builds. Differential Revision: https://phab.mercurial-scm.org/D3431