rfc.sh: Include BUG: header even in first run

Set the commit hook before entiring editor mode. This fixes the
error where rfc.sh after first clone does not set BUG: header

Change-Id: Ic0e9f2d3f656bc81e29d35556022fbdff2f61225
BUG: 764890
Signed-off-by: Anand Avati <avati@redhat.com>
Reviewed-on: http://review.gluster.org/5632

rfc.sh

@@ -85,13 +85,13 @@ assert_diverge()
 
 main()
 {
+    set_hooks_commit_msg;
+
     if [ -e "$1" ]; then
         editor_mode "$@";
         return;
     fi
 
-    set_hooks_commit_msg;
-
     rebase_changes;
 
     assert_diverge;