tests/test-mq-subrepo-svn.t

documentation: add some internals documentation about bid merge

This is an important algorithm that was only documented on the wiki so far.

Some update to the algorithm (and associated doc) is to expected in the future
since the bid merge algorithm is bug-ridden when it comes to file deletion comes
to play.

Differential Revision: https://phab.mercurial-scm.org/D8711

#require svn13

  $ cat <<EOF >> $HGRCPATH
  > [extensions]
  > mq =
  > [diff]
  > nodates = 1
  > [subrepos]
  > allowed = true
  > svn:allowed = true
  > EOF

fn to create new repository, and cd into it
  $ mkrepo() {
  >     hg init $1
  >     cd $1
  >     hg qinit
  > }


handle svn subrepos safely

  $ svnadmin create svn-repo-2499

  $ SVNREPOPATH=`pwd`/svn-repo-2499/project
  $ SVNREPOURL="`"$PYTHON" $TESTDIR/svnurlof.py \"$SVNREPOPATH\"`"

  $ mkdir -p svn-project-2499/trunk
  $ svn import -qm 'init project' svn-project-2499 "$SVNREPOURL"

qnew on repo w/svn subrepo
  $ mkrepo repo-2499-svn-subrepo
  $ svn co "$SVNREPOURL"/trunk sub
  Checked out revision 1.
  $ echo 'sub = [svn]sub' >> .hgsub
  $ hg add .hgsub
  $ hg status -S -X '**/format'
  A .hgsub
  $ hg qnew -m0 0.diff
  $ cd sub
  $ echo a > a
  $ svn add a
  A         a
  $ svn st
  A*    a (glob)
  $ cd ..
  $ hg status -S        # doesn't show status for svn subrepos (yet)
  $ hg qnew -m1 1.diff
  abort: uncommitted changes in subrepository "sub"
  [255]

  $ cd ..