MDEV-19224 Assertion `marked_for_read()' failed

Problem was that wrong key_info variable was used, which caused UNIQUE
key to be used as a covering key

mysql-test/main/unique.result

+CREATE TABLE t1 (pk INT AUTO_INCREMENT PRIMARY KEY, a varchar(30000), UNIQUE (a)) ENGINE=innodb;
+INSERT INTO t1 (a) VALUES (20),(NULL),(NULL),(NULL),(NULL),(NULL),(NULL);
+SELECT * FROM t1 WHERE a BETWEEN '1' AND '100';
+pk	a
+DROP TABLE t1;
 CREATE TABLE t2 (n BLOB, UNIQUE(n));
 INSERT INTO t2 VALUES (1);
 DELETE FROM t2 WHERE n = 1;

mysql-test/main/unique.test

 --source include/have_innodb.inc
 
+#
+# MDEV-19224 Assertion `marked_for_read()' failed in various places with long
+# unique key
+#
+
+CREATE TABLE t1 (pk INT AUTO_INCREMENT PRIMARY KEY, a varchar(30000), UNIQUE (a)) ENGINE=innodb;
+INSERT INTO t1 (a) VALUES (20),(NULL),(NULL),(NULL),(NULL),(NULL),(NULL);
+SELECT * FROM t1 WHERE a BETWEEN '1' AND '100';
+DROP TABLE t1;
+
 #
 # MDEV-19252 Warning about assertion failure marked_for_write_or_computed()
 # printed by release build with DBUG_ASSERT_AS_PRINTF, but no failure on debug

sql/table.cc

@@ -2690,7 +2690,7 @@ int TABLE_SHARE::init_from_binary_frm_image(THD *thd, bool write,
           field->key_start.set_bit(key);
         if (field->key_length() == key_part->length &&
             !(field->flags & BLOB_FLAG) &&
-            key_info->algorithm != HA_KEY_ALG_LONG_HASH)
+            keyinfo->algorithm != HA_KEY_ALG_LONG_HASH)
         {
           if (handler_file->index_flags(key, i, 0) & HA_KEYREAD_ONLY)
           {
@@ -9409,6 +9409,7 @@ bool vers_select_conds_t::eq(const vers_select_conds_t &conds) const
     return true;
   case SYSTEM_TIME_BEFORE:
     DBUG_ASSERT(0);
+    return false;
   case SYSTEM_TIME_AS_OF:
     return start.eq(conds.start);
   case SYSTEM_TIME_FROM_TO: