diff -ru boost.orig/boost/libs/locale/src/encoding/codepage.cpp boost/boost/libs/locale/src/encoding/codepage.cpp
--- foo/misc/boost.orig/libs/locale/src/encoding/codepage.cpp
+++ foo/misc/boost/libs/locale/src/boost/locale/encoding/codepage.cpp
@@ -52,6 +52,9 @@
         }
 #endif
 #endif
+        // ensures we get a sensible warning in boost's gettext results about a real mismatch.
+        if (to_charset == from_charset)
+            return std::string(begin, end - begin);
         throw invalid_charset_error(std::string(to_charset) + " or " + from_charset);
     }