histedit: rip out mysterious catch-all ignore curses.error handler I have no idea why this was here, and ripping it out doesn't obviously break anything for me (tests all pass, I can poke around chistedit UI a bit without issue), so I'm thinking we should rip it out and see if we get bug reports. Differential Revision: https://phab.mercurial-scm.org/D9855

histedit: notice when the main window underflows height and abort If you try to have a 13-line-tall terminal and use curses histedit, it fails by spinning in an infinite loop due to the catch-all ignore of curses errors on line 1682 of histedit.py. We should also fix that catch-all ignore of curses errors (what other demons lurk here, I wonder?) but we can trivially catch this case and guide the user to a happy path. We've seen this mostly in IDE users that have a tendency to have really tiny embedded terminal windows. Differential Revision: https://phab.mercurial-scm.org/D9854

histedit: don't assign to _ for unused values I don't know what this ignored value is, but we need to not clobber the _() function from gettext, or we get mysterious crashes instead of internationalizing some strings in my upcoming patches. Differential Revision: https://phab.mercurial-scm.org/D9853

hghave: list the module needed for the `vcr` check I'm tired of having to look up modules each time I setup a system, and try to distinguish between similar package names to get the right one. Now that the search API has been disabled, it's even harder. There are other python packages here that should be listed like this, but this is the one that came up missing today, so it's a start. Differential Revision: https://phab.mercurial-scm.org/D9879

debugshell: add a simple command for starting an interactive shell This simplifies interactive exploration of the Mercurial APIs. The ui and repo instances are provided as local variables. Differential Revision: https://phab.mercurial-scm.org/D9866

rust: replace an unsafe use of transmute with a safe use of bytes-cast Differential Revision: https://phab.mercurial-scm.org/D9859

rust: use the bytes-cast crate to parse persistent nodemaps This crate casts pointers to custom structs, with compile-time safety checks, for easy and efficient binary data parsing. See https://crates.io/crates/bytes-cast and https://docs.rs/bytes-cast/0.1.0/bytes_cast/ Differential Revision: https://phab.mercurial-scm.org/D9788

cext: restore the ability to build on Windows with py2 This broke in e92ca942ddca. Differential Revision: https://phab.mercurial-scm.org/D9867

command-namespace: use `::` are the command separator This was discussed on the mailing list / phab and `::` got a couple of positive feedback. I dediced to not introduce automatic folding of `::`, I feel like it make sense for `-`, but I like the expliciteness of `::`. So I am adding alias for backward compatibility. Differential Revision: https://phab.mercurial-scm.org/D9872

perf: test the formatting of a command help Since we are about to addd ':' in command name I want this covered. Differential Revision: https://phab.mercurial-scm.org/D9871