Sync with 1.9.1

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --combined Documentation/git.txt
index 27a199ca1af53c25f7b3e41501402244b11614d4,c7b135dbe51a1e7dbcabdf81606a6b8c401d59b7..e5f8ed0940d296613a05d3b23981215e39a5ba1a
--- 1/Documentation/git.txt
--- 2/Documentation/git.txt
+++ b/Documentation/git.txt
@@@ -43,9 -43,10 +43,10 @@@ unreleased) version of Git, that is ava
  branch of the `git.git` repository.
  Documentation for older releases are available here:
  
- * link:v1.9.0/git.html[documentation for release 1.9.0]
+ * link:v1.9.1/git.html[documentation for release 1.9.1]
  
  * release notes for
+   link:RelNotes/1.9.1.txt[1.9.1],
    link:RelNotes/1.9.0.txt[1.9.0].
  
  * link:v1.8.5.5/git.html[documentation for release 1.8.5.5]
@@@ -720,11 -721,6 +721,11 @@@ Git so take care if using Cogito etc
        index file. If not specified, the default of `$GIT_DIR/index`
        is used.
  
 +'GIT_INDEX_VERSION'::
 +      This environment variable allows the specification of an index
 +      version for new repositories.  It won't affect existing index
 +      files.  By default index file version [23] is used.
 +
  'GIT_OBJECT_DIRECTORY'::
        If the object storage directory is specified via this
        environment variable then the sha1 directories are created