help: document the minimumhgversion variable for extensions

help: modernize the example for command registration

Added signature for changeset 593718ff5844

Added tag 4.9rc0 for changeset 593718ff5844

merge default into stable for 4.9 release

update: fix edge-case with update.atomic-file and read-only files We used to create the tempfile with the original file mode. That means creating a read-only tempfile when the original file is read-only, which crash if we need to write on the tempfile. The file in the working directory ends up being writable with and without the atomic update config, so the behavior is the same.

scmutil: drop unreachable except clause socket.error is a subclass of IOError, which we catch higher up. It seems to have been this way since 020a896a5292 (dispatch: sort exception handlers, 2009-01-12), so let's celebrate the 10 year anniversary (a few days late) of it being wrong by deleting it. Differential Revision: https://phab.mercurial-scm.org/D5626

tests: suppress "Checked out 1 paths of <hash>" from modern git test-convert-git.t is failiing since git commit 0f086e6dca (checkout: print something when checking out paths, 2018-11-13). Suppress the new output by disambiguating the arguments with a "--" separator. Differential Revision: https://phab.mercurial-scm.org/D5625

revlog: document that mmap resources are released implicitly by GC It's okay-ish, but currently the open fd and the mapping itself are leaked until the indexdata is deallocated. If revlog had close(), the underlying resources should be closed there as well, but AFAIK there's no such hook point.

ui: proxy protect/restorestdio() calls to update internal flag It should be better to manage the redirection flag solely by the ui class.