[PATCH 7 of 8] branchmap: remove use of buffer() to support Python 2.6

[FUJIWARA Katsunori]

At Thu, 8 Jun 2017 12:13:27 -0700,
Gregory Szorc wrote:
> 
> [1  <text/plain; UTF-8 (7bit)>]
> On Thu, Jun 8, 2017 at 11:41 AM, Augie Fackler <raf at durin42.com> wrote:
> 
> >
> > > On Jun 8, 2017, at 12:02, FUJIWARA Katsunori <foozy at lares.dti.ne.jp>
> > wrote:
> > >
> > > At Sat, 13 May 2017 12:54:39 -0700,
> > > Gregory Szorc wrote:
> > >>
> > >> # HG changeset patch
> > >> # User Gregory Szorc <gregory.szorc at gmail.com>
> > >> # Date 1494701888 25200
> > >> #      Sat May 13 11:58:08 2017 -0700
> > >> # Node ID d407296a5efc9710584087d23e4ff9293d7fb6ef
> > >> # Parent  016157858ae7e60681163ba47dca6ba822319dbe
> > >> branchmap: remove use of buffer() to support Python 2.6
> > >>
> > >> The use of buffer() was added in 7359157b9e46 to support Python 2.6,
> > >> which we no longer support.
> > >
> > > For SupportedPythonVersions wiki page and release note of coming
> > > Mercurial 4.3 :-)
> > >
> > > This unpacking feature seems available with Python 2.7.4 (released at
> > > 2013-04-06) or later, as "fixing issue10212".
> > >
> > >  https://hg.python.org/cpython/raw-file/v2.7.4/Misc/NEWS
> > >  https://bugs.python.org/issue10212
> > >
> > > I confirmed that this patch causes failure in this code path with
> > > Python 2.7.3 at least.
> >
> > I think I'm inclined to tell people that 2.7.4 is the minimum, given that
> > we *really* want people on something that's 2.7.10 or thereabouts anyway so
> > they get proper modern TLS.
> >

I found one more breakage point.

Python 2.7.4 - 2.7.9 fails at creating zip archive on hgweb server
side, because Python zipfile module tries to invoke "seek" method on
wsgirequest object (defined in mercurial/hgweb/request.py), even
though it doesn't provide it.

This can reproduce by test-archive.t.

This unintentional "seek" invocation is recognized as issue14099 of
Python, and fixed at 2.7.10.

    https://bugs.python.org/issue14099

So, let's require 2.7.10 or later :-)

> Firefox's build system has required Python 2.7.3+ since September 2013 (
> https://bugzilla.mozilla.org/show_bug.cgi?id=870420) (because we were tired
> of working around bugs in older Python versions). AFAIK nobody has
> complained about it in ages. So my experience says Mercurial can also get
> away with requiring a minimum version of 2.7. In reality, this should only
> impact Linux and Unixen as OS X and Windows are taken care of via our
> packaging or Homebrew/MacPorts.

We need to update files below ?

  contrib/debian/control
  contrib/mercurial.spec

> >
> > >
> > >> diff --git a/mercurial/branchmap.py b/mercurial/branchmap.py
> > >> --- a/mercurial/branchmap.py
> > >> +++ b/mercurial/branchmap.py
> > >> @@ -406,8 +406,7 @@ class revbranchcache(object):
> > >>
> > >>         # fast path: extract data from cache, use it if node is matching
> > >>         reponode = changelog.node(rev)[:_rbcnodelen]
> > >> -        cachenode, branchidx = unpack_from(
> > >> -            _rbcrecfmt, util.buffer(self._rbcrevs), rbcrevidx)
> > >> +        cachenode, branchidx = unpack_from(_rbcrecfmt, self._rbcrevs,
> > rbcrevidx)
> > >>         close = bool(branchidx & _rbccloseflag)
> > >>         if close:
> > >>             branchidx &= _rbcbranchidxmask
> > >> _______________________________________________
> > >> Mercurial-devel mailing list
> > >> Mercurial-devel at mercurial-scm.org
> > >> https://www.mercurial-scm.org/mailman/listinfo/mercurial-devel
> > >
> > > --
> > > ----------------------------------------------------------------------
> > > [FUJIWARA Katsunori]                             foozy at lares.dti.ne.jp
> > > _______________________________________________
> > > Mercurial-devel mailing list
> > > Mercurial-devel at mercurial-scm.org
> > > https://www.mercurial-scm.org/mailman/listinfo/mercurial-devel
> >
> >
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-- 
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[FUJIWARA Katsunori]                             foozy at lares.dti.ne.jp