phase: use context managers for lock and transaction Differential Revision: https://phab.mercurial-scm.org/D1838

obsolete: use context manager for transaction in pushmarker() Differential Revision: https://phab.mercurial-scm.org/D1837

obsolete: use context manager for lock in pushmarker() Differential Revision: https://phab.mercurial-scm.org/D1836

obsolete: use context manager for transaction in createmarkers() Differential Revision: https://phab.mercurial-scm.org/D1835

visibility: improve the message when accessing filtered obsolete rev When trying to access filtered revision, it is likely because they have been obsoleted by an obs-marker. The current message shows how to access the revision anyway: abort: hidden revision '13bedc178fce'! But in the case of an obsoleted revision, the user is likely to want to update to or use the successor of the revision. We update the message to display more information about the obsolescence fate of the revision in the following cases: abort: hidden revision '13bedc178fce' is pruned! abort: hidden revision '13bedc178fce' has diverged! abort: hidden revision '13bedc178fce' was rewritten as X, Y and 2 more! Differential Revision: https://phab.mercurial-scm.org/D1591

tests: add b'' to string literals where bytes are required Since we are internally dealing with bytes only, we need to use bytes in the tests too. This is one of the many patches which will make all the tests completely use bytes. # skip-blame because we are just adding b'' Differential Revision: https://phab.mercurial-scm.org/D1788