contrib/xml.rnc

revlog: fix revset in reachableroots docstring

`reachableroots` will only return a subset of `roots` when `includepath` is
False. For example, given the following linear DAG:

  2
  |
  1
  |
  0

Using roots=0+2, heads=1, the definition in the docstring does not match what
`reachableroots` actually does:

  ipdb> repo.changelog.reachableroots(0, roots=[0,2],heads=[1])
  [0]
  ipdb> repo.revs('heads(::(0+2) & (0+2)::1)')
  <baseset+ [1]>

The fix is to do `heads & ::roots` (or `heads & heads::roots`) first, then
select their ancestors:

  ipdb> repo.revs('heads(::((0+2) & (0+2)::1))')
  <baseset+ [0]>

The docstring was introduced by fd92bfbbe02d9 (2015-06-19 "revset: rename
revsbetween to reachableroots and add an argument"), which introduced the
`includepath=False` behavior for graphlog grandparents use-case. I believe
the docstring instead of the code should be changed because changing the
code to match the docstring can result in suboptimal graphlog like:

  o
  :\
  : o
  : :
  :/
  o

As opposite to the current "linearized" graphlog:

  o
  |
  o
  :
  o

Differential Revision: https://phab.mercurial-scm.org/D7518

# RelaxNG schema for "xml" log style
# Inspired by Subversion's XML log format.

start = log
node.type = xsd:string  {minLength = "40" maxLength = "40"}

log = element log { logentry+ }
logentry = element logentry {
    logentry.attlist,
    branch*, tag*, hgparent*,
    author, date,
    msg, paths?, copies?, extra*
}
logentry.attlist =
    attribute revision {xsd:nonNegativeInteger}
  & attribute node {node.type}
branch = element branch { text }
tag = element tag { text }
hgparent = element parent {hgparent.attlist, text}
hgparent.attlist =
    attribute revision {xsd:integer {minInclusive = "-1"} }
  & attribute node {node.type}
author = element author { author.attlist, text }
author.attlist =
    attribute email {text}
date = element date {xsd:dateTime}
msg = element msg {msg.attlist, text}
msg.attlist =
    attribute xml:space {"preserve"}
paths = element paths { path* }
path = element path { path.attlist, text }
path.attlist =
    # Action: (A)dd, (M)odify, (R)emove
    attribute action {"A"|"M"|"R"}
copies = element copies { copy+ }
copy = element copy { copy.attlist, text }
copy.attlist =
    attribute source {text}
extra = element extra {extra.attlist, text}
extra.attlist =
    attribute key {text}