subrepo: normalize path part of URLs so that pulling subrepos from webdir works

For a "all projects at root" repo layout eg:
/main
/sub

Where subrepos are used such that a clone of main has this layout:
./main/
./main/.hgsub
./main/sub/

And the .hgsub content is:
sub = ../sub

This allows a pull from a hgweb where main and sub are exposed
at the root (or same directory level)

The current code doesn't normalize the path component of a pull
url. this results in trying to pull from
http://server.com/hg/main/../sub

Current hgweb implementation doesn't reduce the path component
so this results in a 404 error though everything is setup logically.

This patch adresses this 404 error on the puller side
normalizing the URLs used for pulling sub repos. For this
example, the URL would be reduced to http://server.com/hg/sub

Fix + test

tests/test-subrepo-relative-path

@@ -0,0 +1,40 b''
+#!/bin/sh
+
+echo % Preparing the subrepository 'sub'
+hg init sub
+echo sub > sub/sub
+hg add -R sub
+hg commit -R sub -m "sub import"
+
+echo % Preparing the 'main' repo which depends on the subrepo 'sub'
+hg init main
+echo main > main/main
+echo "sub = ../sub" > main/.hgsub
+hg clone sub main/sub | sed 's/ .*sub/ ...sub/g'
+hg add -R main
+hg commit -R main -m "main import"
+
+echo % Cleaning both repositories, just as a clone -U
+hg up -C -R sub null
+hg up -C -R main null
+rm -rf main/sub
+
+echo % Serving them both using hgweb
+printf '[paths]\n/main = main\nsub = sub\n' > webdir.conf
+hg serve --webdir-conf webdir.conf -a localhost -p $HGPORT \
+   -A /dev/null -E /dev/null --pid-file hg.pid -d
+cat hg.pid >> $DAEMON_PIDS
+
+echo % Clone main from hgweb
+hg clone "http://localhost:$HGPORT/main" cloned | sed 's/ .*sub/ ...sub/g' 
+
+echo % Checking cloned repo ids
+hg id -R cloned
+hg id -R cloned/sub
+
+echo % subrepo debug for 'main' clone
+hg debugsub -R cloned
+
+"$TESTDIR/killdaemons.py"
+
+exit 0

tests/test-subrepo-relative-path.out

@@ -0,0 +1,33 b''
+% Preparing the subrepository sub
+adding sub/sub
+% Preparing the main repo which depends on the subrepo sub
+updating to branch default
+1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+adding main/.hgsub
+adding main/main
+committing subrepository sub
+% Cleaning both repositories, just as a clone -U
+0 files updated, 0 files merged, 1 files removed, 0 files unresolved
+0 files updated, 0 files merged, 3 files removed, 0 files unresolved
+% Serving them both using hgweb
+% Clone main from hgweb
+requesting all changes
+adding changesets
+adding manifests
+adding file changes
+added 1 changesets with 3 changes to 3 files
+updating to branch default
+pulling ...sub
+requesting all changes
+adding changesets
+adding manifests
+adding file changes
+added 1 changesets with 1 changes to 1 files
+3 files updated, 0 files merged, 0 files removed, 0 files unresolved
+% Checking cloned repo ids
+fdfeeb3e979e tip
+863c1745b441 tip
+% subrepo debug for main clone
+path sub
+ source   ../sub
+ revision 863c1745b441bd97a8c4a096e87793073f4fb215

mercurial/subrepo.py

@@ -5,7 +5,7 b''
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
-import errno, os, re, xml.dom.minidom, shutil
+import errno, os, re, xml.dom.minidom, shutil, urlparse, posixpath
 from i18n import _
 import config, util, node, error
 hg = None
@@ -135,8 +135,12 b' def _abssource(repo, push=False):'
         if '://' in parent:
             if parent[-1] == '/':
                 parent = parent[:-1]
-            return parent + '/' + source
-        return os.path.join(parent, repo._subsource)
+            r = urlparse.urlparse(parent + '/' + source)
+            r = urlparse.urlunparse((r[0], r[1],
+                                     posixpath.normpath(r.path),
+                                     r[3], r[4], r[5]))
+            return r
+        return posixpath.normpath(os.path.join(parent, repo._subsource))
     if push and repo.ui.config('paths', 'default-push'):
         return repo.ui.config('paths', 'default-push', repo.root)
     return repo.ui.config('paths', 'default', repo.root)

tests/test-subrepo.out

@@ -275,7 +275,7 b' 2 files updated, 0 files merged, 0 files'
 [paths]
 default = $HGTMP/test-subrepo/sub/mercurial/nested_absolute
 [paths]
-default = $HGTMP/test-subrepo/sub/mercurial/main/../nested_relative
+default = $HGTMP/test-subrepo/sub/mercurial/nested_relative
 % issue 1977
 adding a
 adding .hgsub