Index: contrib/client-side/svnmerge.py
===================================================================
--- contrib/client-side/svnmerge.py	(revision 19196)
+++ contrib/client-side/svnmerge.py	(working copy)
@@ -937,6 +937,13 @@
            (branch_dir, revs, opts["head-url"]))
 
     revs = str(revs)
+    # if the head-path already has an entry
+    # in the svnmerge-integrated property,
+    # simply error out.
+    if not opts["force"] and branch_props.has_key(opts["head-path"]):
+      err_msg  = opts["head-path"] + " has already been initialized at "
+      err_msg += branch_dir + "\nUse --force to force re-init"
+      error(err_msg)
     branch_props[opts["head-path"]] = revs
 
     # Set property