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

stream-clone-tests: stop filtering non existent warning This filtering was introduced in 74c004a515bc, however there is already no warning in that changeset. So I guess the warnings existed when we the patch was created but the problem was solved in another changeset that 74c004a515bc, rebased on.

stream-clone-test: simplify case testing obsolescence There is only two important things in this test: - the number of file we send, to show we picked the obsstore. - the resulting state, to show we did alter things in the process. The rest are of the number are very fragile and consume a lot of time for little value when adjusting formats, caches, and protocol.

stream-clone-test: simplify the case testing phases There is only two important things in this test: - the number of file we send, to show we picked the phase roots. - the resulting phases, to show we did not modified them. The rest are of the number are very fragile and consume a lot of time for little value when adjusting formats, caches, and protocol.