diff --git a/obs-service-tar_scm.changes b/obs-service-tar_scm.changes
index 3132c49..a52aa83 100644
--- a/obs-service-tar_scm.changes
+++ b/obs-service-tar_scm.changes
@@ -1,3 +1,10 @@
+-------------------------------------------------------------------
+Thu May 24 00:57:28 GMT 2012 - rohan.mcgovern@nokia.com
+
+- Allow git revision to refer to revisions not available from a
+  default clone/fetch (i.e. refs other than refs/heads/* or
+  refs/tags/*)
+
 -------------------------------------------------------------------
 Mon Mar 19 13:39:28 GMT 2012 - aspiers@suse.com
 
diff --git a/tar_scm b/tar_scm
index b714fac..2da4a5e 100644
--- a/tar_scm
+++ b/tar_scm
@@ -323,6 +323,23 @@ update_cache () {
 switch_to_revision () {
   case "$MYSCM" in
     git)
+      # $MYREVISION may refer to any of the following:
+      #
+      # - explicit SHA1: a1b2c3d4....
+      #   - the SHA1 must be reachable from a default clone/fetch (generally, must be
+      #     reachable from some branch or tag on the remote).
+      #   - set by: git checkout <SHA1>
+      #
+      # - short branch name: "master", "devel" etc.
+      #   - set by: git checkout <branch> && git pull
+      #
+      # - explicit ref: refs/heads/master, refs/tags/v1.2.3, refs/changes/49/11249/1
+      #   - set by: git fetch <url> +<revision>:<revision> && git checkout <revision>
+      #
+      if ! git rev-parse --verify "$MYREVISION"; then
+        echo "$MYREVISION not accessible by default clone/fetch, attempting explicit fetch"
+        safe_run git fetch "$MYURL" "+$MYREVISION:$MYREVISION"
+      fi
       safe_run git checkout "$MYREVISION"
       if git branch | grep -q '^\* (no branch)$'; then
         echo "$MYREVISION does not refer to a branch, not attempting git pull"