[3899] Removed extra space in error message

src/lib/dhcp/duid.cc

@@ -1,4 +1,4 @@
-// Copyright (C) 2012-2014 Internet Systems Consortium, Inc. ("ISC")
+// Copyright (C) 2012-2015 Internet Systems Consortium, Inc. ("ISC")
 //
 // Permission to use, copy, modify, and/or distribute this software for any
 // purpose with or without fee is hereby granted, provided that the above
@@ -76,7 +76,7 @@ DUID::decode(const std::string& text) {
             // allowed for client identifier.
             if (split_text[i].empty()) {
                 isc_throw(isc::BadValue, "invalid identifier '"
-                          << text << "': " << " tokens must be"
+                          << text << "':" << " tokens must be"
                           " separated with a single colon");
             } else if (split_text[i].size() > 2) {
                 isc_throw(isc::BadValue, "invalid identifier '"