compat: drop 4.5 compatibility for strdiff

compat: drop 4.5 compatibility layer for log utility

compat: drop 4.5 related compatibility around wireprotocol module

compat: directly use status attribute instead of the compat layer With 4.5 dropped, this compat layer is no longer needed.

compat: directly use function from dateutil Since support for 4.5 have been dropped we no longer needs this indirection.

compat: drop 4.5 compatibility for `_filterederror`

compat: drop import compatibility <= 4.5 for `forcebytestr` We no longer support 4.5

tests: adapt now that Mercurial clears the merge state for empty wdir `hg evolve` forgot to clear the merge state when its attempt to commit resulted in no commit because the working copy had no changes. That resulted in test-evolve-issue5967.t showing a conflict state that shouldn't be there. The responsibility for clearing the merge state was moved into Mercurial in Mercurial in 6a34e438461b (commit: clear resolved mergestate even if working copy is clean, 2020-02-28), so the bug is now fixed in `hg evolve`, which impacts that test case. CORE-TEST-OUTPUT-UPDATE: 6a34e438461b

tests: add more involved tests for obslog -T now that everything is a property

obslog: remove the separate "obslog -f" implementation and use the common one