The LANG vars aren't reset early enough so when sed tries to use [a-zA-Z] in 
option parsing, it may break.

http://bugs.gentoo.org/133679

--- configure
+++ configure
@@ -54,6 +54,19 @@
 infodir='${prefix}/info'
 mandir='${prefix}/man'
 
+# NLS nuisances.
+for as_var in \
+  LANG LANGUAGE LC_ADDRESS LC_ALL LC_COLLATE LC_CTYPE LC_IDENTIFICATION \
+  LC_MEASUREMENT LC_MESSAGES LC_MONETARY LC_NAME LC_NUMERIC LC_PAPER \
+  LC_TELEPHONE LC_TIME
+do
+  if (set +x; test -z "`(eval $as_var=C; export $as_var) 2>&1`"); then
+    eval $as_var=C; export $as_var
+  else
+    unset $as_var
+  fi
+done
+
 # Initialize some other variables.
 subdirs=
 MFLAGS= MAKEFLAGS=
@@ -452,16 +463,6 @@
   esac
 done
 
-# NLS nuisances.
-# Only set these to C if already set.  These must not be set unconditionally
-# because not all systems understand e.g. LANG=C (notably SCO).
-# Fixing LC_MESSAGES prevents Solaris sh from translating var values in `set'!
-# Non-C LC_CTYPE values break the ctype check.
-if test "${LANG+set}"   = set; then LANG=C;   export LANG;   fi
-if test "${LC_ALL+set}" = set; then LC_ALL=C; export LC_ALL; fi
-if test "${LC_MESSAGES+set}" = set; then LC_MESSAGES=C; export LC_MESSAGES; fi
-if test "${LC_CTYPE+set}"    = set; then LC_CTYPE=C;    export LC_CTYPE;    fi
-
 # confdefs.h avoids OS command line length limits that DEFS can exceed.
 rm -rf conftest* confdefs.h
 # AIX cpp loses on an empty file, so make sure it contains at least a newline.