+NNG version with a commit ID of 906d5ea1b3d67bece941d8a4e0a049e5f6c65051
+is required to build RMR. That version (as yet untagged) adds a
+new error state which we must trap. While application environments
+are encouraged to also build and install at least this version of
+NNG, RMR is still compatable back to the version tagged as 1.1.1.
+If you opt to build with the -DSKIP_EXTERNALS=1 flag set, you must
+ensure that this version of NNG is present in your build environment.
+If you do not set this flag, the proper NNG source will be used
+automatically.
+