stream-clone-test: simplify the --uncompressed alias check To check that --uncompressed is an alias we just need to check it trigger a stream clone, we don't need to check anything else.

stream-clone-test: drop an automatic pattern replacement That pattern is nice, but it prevent us to glob the number of bytes when we don't care about them. We don't care about them more often that what we currently checks so dropping this pattern will help use to simplify various tests.

stream-clone-test: simplify the test for getbundle with stream=1 The core of this tests is about checking we receive a stream bundle with such request. We don't need to look at too much of the details of the stream itself. Since the content of the stream if shifting overtime, Such check is very fragile and consume a lot of time for little value when adjusting formats, caches, and protocol. So we reduce the size of what we check to focus on "is this a stream clone" question.

stream-clone-test: factor some piece of basic clone test out Multiple parts of this case (listing cache, checking error) are common to all cases and don't need to be in the conditionnal block. This simplify the test update.

stream-clone-test: simplify the case where server disabled it We have an option to disable it, we don't need to test it with all protocol variants. In addition there is little value in looking at the bytes to bytes details of the reply. Such check is very fragile and consume a lot of time for little value when adjusting formats, caches, and protocol.

repoview: prevent `None` to be passed as the filtername We let such instantiation slip in a previous commit, so we add an explicit check to prevent it to happen in the future.

branchcache: avoid created a `None` filter repoview when writing The repoview class is not intended to be used for unfiltered repository.

branchcache: move head writing in a `_write_headers` method Same rational: this will help having format variants.

branchcache: move head writing in a `_write_heads` method Same rational: this will help having format variants.

branchcache: move the header loading in a `_load_header` class method This will help changing header parsing in format variants.