view CONTRIBUTORS @ 33556:22371eabb3b1

sparse: add a requirement when a repository uses sparse (BC)

The presence of a sparse checkout can confuse legacy clients or
clients without sparse enabled for reasons that should be obvious.

This commit introduces a new repository requirement that tracks
whether sparse is enabled. The requirement is added when a sparse
config is activated and removed when the sparse config is reset.

The localrepository constructor has been taught to not open repos
with this requirement unless the sparse feature is enabled. It yields
a more actionable error message than what you would get if the
lockout were handled strictly at the requirements verification phase.
Old clients that aren't sparse aware will see the generic
"repository requires features unknown to this Mercurial" error,
however.

The new requirement has "exp" in its name to reflect the
experimental nature of sparse. There's a chance that the eventual
non-experimental feature won't change significantly and we could
have squatted on the "sparse" requirement without ill effect. If
that happens, we can teach new clients to still recognize the old
name. But I suspect we'll sneak in some BC and we'll want a new
requirement to convey new meaning.

Differential Revision: https://phab.mercurial-scm.org/D110

[This file is here for historical purposes, all recent contributors
should appear in the changelog directly]

Andrea Arcangeli <andrea at suse.de>
Thomas Arendsen Hein <thomas at intevation.de>
Goffredo Baroncelli <kreijack at libero.it>
Muli Ben-Yehuda <mulix at mulix.org>
Mikael Berthe <mikael at lilotux.net>
Benoit Boissinot <bboissin at gmail.com>
Brendan Cully <brendan at kublai.com>
Vincent Danjean <vdanjean.ml at free.fr>
Jake Edge <jake at edge2.net>
Michael Fetterman <michael.fetterman at intel.com>
Edouard Gomez <ed.gomez at free.fr>
Eric Hopper <hopper at omnifarious.org>
Alecs King <alecsk at gmail.com>
Volker Kleinfeld <Volker.Kleinfeld at gmx.de>
Vadim Lebedev <vadim at mbdsys.com>
Christopher Li <hg at chrisli.org>
Chris Mason <mason at suse.com>
Colin McMillen <mcmillen at cs.cmu.edu>
Wojciech Milkowski <wmilkowski at interia.pl>
Chad Netzer <chad.netzer at gmail.com>
Bryan O'Sullivan <bos at serpentine.com>
Vicent Seguí Pascual <vseguip at gmail.com>
Sean Perry <shaleh at speakeasy.net>
Nguyen Anh Quynh <aquynh at gmail.com>
Ollivier Robert <roberto at keltia.freenix.fr>
Alexander Schremmer <alex at alexanderweb.de>
Arun Sharma <arun at sharma-home.net>
Josef "Jeff" Sipek <jeffpc at optonline.net>
Kevin Smith <yarcs at qualitycode.com>
TK Soh <teekaysoh at yahoo.com>
Radoslaw Szkodzinski <astralstorm at gorzow.mm.pl>
Samuel Tardieu <sam at rfc1149.net>
K Thananchayan <thananck at yahoo.com>
Andrew Thompson <andrewkt at aktzero.com>
Michael S. Tsirkin <mst at mellanox.co.il>
Rafael Villar Burke <pachi at mmn-arquitectos.com>
Tristan Wibberley <tristan at wibberley.org>
Mark Williamson <mark.williamson at cl.cam.ac.uk>