subrepo: make "_sanitize()" take absolute path to the root of subrepo

Before this patch, "hg update" doesn't sanitize ".hg/hgrc" in non-hg
subrepos correctly, if "hg update" is executed not at the root of the
parent repository.

"_sanitize()" takes relative path to subrepo from the root of the
parent repository, and passes it to "os.walk()". In this case,
"os.walk()" expects CWD to be equal to the root of the parent
repository.

So, "os.walk()" can't find specified path (or may scan unexpected
path), if CWD isn't equal to the root of the parent repository.

Non-hg subrepo under nested hg-subrepos may cause same problem, too:
CWD may be equal to the root of the outer most repository, or so.

This patch makes "_sanitize()" take absolute path to the root of
subrepo to sanitize correctly in such cases.

This patch doesn't normalize the path to hostile files as the one
relative to CWD (or the root of the outer most repository), to fix the
problem in the simple way suitable for "stable".

Normalizing should be done in the future: maybe as a part of the
migration to vfs.

mercurial/subrepo.py

@@ -1050,7 +1050,7 b' class svnsubrepo(abstractsubrepo):'
         # update to a directory which has since been deleted and recreated.
         args.append('%s@%s' % (state[0], state[1]))
         status, err = self._svncommand(args, failok=True)
-        _sanitize(self._ui, self._path)
+        _sanitize(self._ui, self._ctx._repo.wjoin(self._path))
         if not re.search('Checked out revision [0-9]+.', status):
             if ('is already a working copy for a different URL' in err
                 and (self._wcchanged()[:2] == (False, False))):
@@ -1343,7 +1343,7 b' class gitsubrepo(abstractsubrepo):'
                 self._gitcommand(['reset', 'HEAD'])
                 cmd.append('-f')
             self._gitcommand(cmd + args)
-            _sanitize(self._ui, self._path)
+            _sanitize(self._ui, self._abspath)
 
         def rawcheckout():
             # no branch to checkout, check it out with no branch
@@ -1392,7 +1392,7 b' class gitsubrepo(abstractsubrepo):'
             if tracking[remote] != self._gitcurrentbranch():
                 checkout([tracking[remote]])
             self._gitcommand(['merge', '--ff', remote])
-            _sanitize(self._ui, self._path)
+            _sanitize(self._ui, self._abspath)
         else:
             # a real merge would be required, just checkout the revision
             rawcheckout()
@@ -1428,7 +1428,7 b' class gitsubrepo(abstractsubrepo):'
                 self.get(state) # fast forward merge
             elif base != self._state[1]:
                 self._gitcommand(['merge', '--no-commit', revision])
-            _sanitize(self._ui, self._path)
+            _sanitize(self._ui, self._abspath)
 
         if self.dirty():
             if self._gitstate() != revision:

tests/test-subrepo-git.t

@@ -592,11 +592,11 b' Test sanitizing ".hg/hgrc" in subrepo'
   c4069473b459cf27fd4d7c2f50c4346b4e936599 s
   $ cd ..
 
+  $ hg -R tc pull -q
+  $ hg -R tc update -q -C 3473d20bddcf 2>&1 | sort
+  warning: removing potentially hostile 'hgrc' in '$TESTTMP/tc/s/.hg' (glob)
+  warning: removing potentially hostile 'hgrc' in '$TESTTMP/tc/s/sub/.hg' (glob)
   $ cd tc
-  $ hg pull -q
-  $ hg update -q -C 3473d20bddcf 2>&1 | sort
-  warning: removing potentially hostile 'hgrc' in 's/.hg' (glob)
-  warning: removing potentially hostile 'hgrc' in 's/sub/.hg' (glob)
   $ hg parents -q
   8:3473d20bddcf
   $ grep ' s$' .hgsubstate
@@ -642,10 +642,12 b' additional test for "git merge --ff" rou'
   $ cat s/sub/.hg/hgrc
   cat: s/sub/.hg/hgrc: No such file or directory
   [1]
-  $ hg pull -q
-  $ hg update -q -C ed23f7fe024e 2>&1 | sort
-  warning: removing potentially hostile 'hgrc' in 's/.hg' (glob)
-  warning: removing potentially hostile 'hgrc' in 's/sub/.hg' (glob)
+  $ cd ..
+  $ hg -R tc pull -q
+  $ hg -R tc update -q -C ed23f7fe024e 2>&1 | sort
+  warning: removing potentially hostile 'hgrc' in '$TESTTMP/tc/s/.hg' (glob)
+  warning: removing potentially hostile 'hgrc' in '$TESTTMP/tc/s/sub/.hg' (glob)
+  $ cd tc
   $ hg parents -q
   9:ed23f7fe024e
   $ grep ' s$' .hgsubstate

tests/test-subrepo-svn.t

@@ -663,10 +663,10 b' Test sanitizing ".hg/hgrc" in subrepo'
   16 s
   $ cd ..
 
+  $ hg -R tc pull -u -q 2>&1 | sort
+  warning: removing potentially hostile 'hgrc' in '$TESTTMP/sub/tc/s/.hg' (glob)
+  warning: removing potentially hostile 'hgrc' in '$TESTTMP/sub/tc/s/sub/.hg' (glob)
   $ cd tc
-  $ hg pull -u -q 2>&1 | sort
-  warning: removing potentially hostile 'hgrc' in 's/.hg' (glob)
-  warning: removing potentially hostile 'hgrc' in 's/sub/.hg' (glob)
   $ grep ' s$' .hgsubstate
   16 s
   $ cat s/.hg/hgrc