diff -ru postgresql-11.4/src/backend/utils/adt/selfuncs.c postgresql-11.4-fix/src/backend/utils/adt/selfuncs.c
--- postgresql-11.4/src/backend/utils/adt/selfuncs.c	2019-06-17 23:15:30.000000000 +0200
+++ postgresql-11.4-fix/src/backend/utils/adt/selfuncs.c	2019-07-04 18:28:26.097870673 +0200
@@ -5770,7 +5770,7 @@
 	else if (is_multibyte && IS_HIGHBIT_SET(c))
 		return true;
 	else if (locale && locale->provider == COLLPROVIDER_ICU)
-		return IS_HIGHBIT_SET(c) ? true : false;
+		return true; /* IS_HIGHBIT_SET(c) ? true : false; */
 #ifdef HAVE_LOCALE_T
 	else if (locale && locale->provider == COLLPROVIDER_LIBC)
 		return isalpha_l((unsigned char) c, locale->info.lt);
Only in postgresql-11.4-fix/src/backend/utils/adt: selfuncs.c~