Bug#29461: Sort order of the collation wasn't used when comparing characters

with the space character.

When the my_strnncollsp_simple function compares two strings and one is a prefix
of another then this function compares characters in the rest of longer key
with the space character to find whether the longer key is greater or less.
But the sort order of the collation isn't used in this comparison. This may
lead to a wrong comparison result, wrongly created index or wrong order of the
result set of a query with the ORDER BY clause.

Now the my_strnncollsp_simple function uses collation sort order to compare
the characters in the rest of longer key with the space character.

mysql-test/r/ctype_collate.result

@@ -603,3 +603,11 @@ check table t1 extended;
 Table	Op	Msg_type	Msg_text
 test.t1	check	status	OK
 drop table t1;
+create table t1 (a varchar(2) character set latin7 collate latin7_general_ci,key(a));
+insert into t1 set a=0x4c20;
+insert into t1 set a=0x6c;
+insert into t1 set a=0x4c98;
+check table t1 extended;
+Table	Op	Msg_type	Msg_text
+test.t1	check	status	OK
+drop table t1;

mysql-test/t/ctype_collate.test

@@ -218,3 +218,14 @@ insert into t1 set f1=0x3F3F1E563F;
 insert into t1 set f1=0x3F3F;
 check table t1 extended;
 drop table t1;
+
+#
+# Bug#29461: Sort order of the collation wasn't used when comparing characters
+#            with the space character.
+#
+create table t1 (a varchar(2) character set latin7 collate latin7_general_ci,key(a));
+insert into t1 set a=0x4c20;
+insert into t1 set a=0x6c;
+insert into t1 set a=0x4c98;
+check table t1 extended;
+drop table t1;

strings/ctype-simple.c

@@ -179,7 +179,7 @@ int my_strnncollsp_simple(CHARSET_INFO * cs, const uchar *a, uint a_length,
     }
     for (end= a + a_length-length; a < end ; a++)
     {
-      if (*a != ' ')
+      if (map[*a] != ' ')
 	return (map[*a] < ' ') ? -swap : swap;
     }
   }