The following obvious patch is needed for the memcoll change in 6.0.
I didn't notice it in my quick test as I had forgotten I changed
xmemcoll to memcoll in uniq in my tree.

I only noticed errno non zero for me when I redirect uniq to >/dev/null
but I guess there are a million other platform/invocation combinations
that will trigger this.

--- memcoll.c	2006-08-14 21:17:25.000000000 +0000
+++ memcoll-errno.c	2006-08-16 06:50:28.000000000 +0000
@@ -43,7 +43,10 @@
      the buffers using strcoll on each substring.  */
 
   if (s1len == s2len && memcmp (s1, s2, s1len) == 0)
-    diff = 0;
+    {
+      diff = 0;
+      errno = 0;
+    }
   else
     {
       char n1 = s1[s1len];