[PATCH 4 of 4 V2] serve: restore the index file for `hg serve -S`

[Matt Harbison]

# HG changeset patch
# User Matt Harbison <matt_harbison at yahoo.com>
# Date 1487129917 18000
#      Tue Feb 14 22:38:37 2017 -0500
# Node ID 3a0c0f139204e6fa86af22c1d54d8c1dd7a4aa2b
# Parent  38babd487181374325f3d27c5bc081dadf31b9b9
serve: restore the index file for `hg serve -S`

There's currently no integration of subrepos into the browsable directory
listing for the parent repo, so this is a nice to have.  The redirect is only
necessary for a Mercurial client.  The comment in mercurial.url.opener() seems
to indicate that the 'Accept' header will always be around for BC.  Another
option to detect a Mercurial client is to check the Request URI for the
capabilities command.

diff --git a/mercurial/hgweb/hgwebdir_mod.py b/mercurial/hgweb/hgwebdir_mod.py
--- a/mercurial/hgweb/hgwebdir_mod.py
+++ b/mercurial/hgweb/hgwebdir_mod.py
@@ -255,10 +255,11 @@
                 staticfile(static, fname, req)
                 return []
 
-            # top-level index
+            # top-level index, or HTTP_MOVED_PERMANENTLY for a Mercurial client
+            # when the server is invoked with --subrepos.
             elif not virtual:
-                if self._rootrepo:
-                    # Redirect '/' to the main repo when -S is given.
+                accept = req.env.get('HTTP_ACCEPT', "")
+                if self._rootrepo and accept == 'application/mercurial-0.1':
                     path = '/' + self._rootrepo
                     if self.prefix:
                         path = '/' + self.prefix + path
diff --git a/tests/test-subrepo-recursion.t b/tests/test-subrepo-recursion.t
--- a/tests/test-subrepo-recursion.t
+++ b/tests/test-subrepo-recursion.t
@@ -295,6 +295,10 @@
   z2
   z3
 
+  $ wget -q http://localhost:$HGPORT
+  $ cat index.html | grep '<title>'
+  <title>Mercurial repositories index</title>
+
   $ cat access.log
   * "GET /?cmd=capabilities HTTP/1.1" 301 - (glob)
   * "GET /repo HTTP/1.1" 200 - (glob)
@@ -308,9 +312,10 @@
   * "GET /repo/foo/bar?cmd=capabilities HTTP/1.1" 200 - (glob)
   * "GET /repo/foo/bar?cmd=batch HTTP/1.1" 200 - * (glob)
   * "GET /repo/foo/bar?cmd=getbundle HTTP/1.1" 200 - * (glob)
+  * "GET / HTTP/1.0" 200 - (glob)
 
   $ killdaemons.py
-  $ rm hg1.pid error.log access.log
+  $ rm hg1.pid error.log access.log index.html
   $ cd repo
 #endif