test-bad-http-server: introduce sock closing when writing a pattern Instead of using a fixed number a bytes, a very unstable method. We introduce a new config that can define a regex. One this regex is detected, nothing after it will be written and the socket will be closed. Tests will be migrated to this new method in later changesets. Differential Revision: https://phab.mercurial-scm.org/D12049

test-http-bad-server: document that the value are actually a list I don't really expect this doc to be read a lot, but mentioning that this is a list seems important. Differential Revision: https://phab.mercurial-scm.org/D12048

test-http-bad-server: refactor the writing logic to avoid early return Our ultimate goal is to add another way to define the connection needs to be closed. To do so, we need the "read" code to be more unified. Differential Revision: https://phab.mercurial-scm.org/D12047

test-http-bad-server: replace the default 65537 value in output This is the default block value that we use here and it make the output overall less readable. So we replace it with `~` Differential Revision: https://phab.mercurial-scm.org/D12046

test-http-bad-server: refactor the reading logic to avoid early return Our ultimate goal is to add another way to define the connection needs to be closed. To do so, we need the "read" code to be more unified. Differential Revision: https://phab.mercurial-scm.org/D12045

test-http-bad-server: factor code dealing with "read" in the new object This will make sure both `read` and `readline` do the same processing and make it simpler to update that processing in the future. Differential Revision: https://phab.mercurial-scm.org/D12044

test-http-bad-server: factor code dealing with "write" in the new object This will make sure both `sendall` and `write` do the same processing and make it simpler to update that processing in the future. Differential Revision: https://phab.mercurial-scm.org/D12043

test-http-bad-server: unify log printing for `sendall` and `write` The `write` function was logging before calling the function while the `sendall` function were logging after calling the function. We align the `write` behavior on the `sendall` behavior before unifying the code. Differential Revision: https://phab.mercurial-scm.org/D12042

test-http-bad-server: track close condition in an object In order to make the logic more advanced, we need to unify it. To unify it, we introduce a small object that will be responsible for tracking and enforcing "premature socket close" conditions for both proxy object (socketproxy and fileobjectproxy). More logic will be moved into the object in later changesets. Differential Revision: https://phab.mercurial-scm.org/D12041

test-http-bad-server: use more readable name for variable This make the code more accessible overall. Differential Revision: https://phab.mercurial-scm.org/D12040