Better fix for bug #3749 (bug in deleting automatic generated foreign keys)

mysql-test/r/func_encrypt.result:
  Update tests (left after sanjas last push)
mysql-test/r/innodb.result:
  Added test for bug #3749 (bug in deleting automatic generated foreign keys)
mysql-test/t/innodb.test:
  Added test for bug #3749 (bug in deleting automatic generated foreign keys)
sql/sql_class.cc:
  Updated comment
tests/client_test.c:
  Added missing mysql_stmt_close()

2 files changed, 10 insertions, 16 deletions

diff --git a/sql/sql_class.cc b/sql/sql_class.cc
index 03d67c4f300..f7992c3db9e 100644
--- a/sql/sql_class.cc
+++ b/sql/sql_class.cc
@@ -86,7 +86,7 @@ bool key_part_spec::operator==(const key_part_spec& other) const
 
 
 /*
-  Test if a foreign key is a prefix of the given key
+  Test if a foreign key (= generated key) is a prefix of the given key
   (ignoring key name, key type and order of columns)
 
   NOTES:
diff --git a/sql/sql_table.cc b/sql/sql_table.cc
index 47574eab666..284b228567a 100644
--- a/sql/sql_table.cc
+++ b/sql/sql_table.cc
@@ -684,11 +684,13 @@ int mysql_prepare_table(THD *thd, HA_CREATE_INFO *create_info,
       while ((key2 = key_iterator2++) != key)
       {
 	/*
-        foreign_key_prefix(key, key2) returns 0 if key or key2, or both, is
-	'generated', and a generated key is a prefix of the other key. Then we
-	do not need the generated shorter key.
+          foreign_key_prefix(key, key2) returns 0 if key or key2, or both, is
+          'generated', and a generated key is a prefix of the other key.
+          Then we do not need the generated shorter key.
         */
-        if ((key2->type != Key::FOREIGN_KEY && !foreign_key_prefix(key, key2)))
+        if ((key2->type != Key::FOREIGN_KEY &&
+             key2->name != ignore_key &&
+             !foreign_key_prefix(key, key2)))
         {
           /* TO DO: issue warning message */
           /* mark that the generated key should be ignored */
@@ -698,17 +700,9 @@ int mysql_prepare_table(THD *thd, HA_CREATE_INFO *create_info,
             key->name= ignore_key;
           else
           {
-            /*
-	    Remove the previous, generated key if it has not yet been
-	    removed. Note that if we have several identical generated keys,
-            the last one will remain and others get removed here.
-	    */
-            if (key2->name != ignore_key)
-            {
-              key2->name= ignore_key;
-              key_parts-= key2->columns.elements;
-              (*key_count)--;
-            }
+            key2->name= ignore_key;
+            key_parts-= key2->columns.elements;
+            (*key_count)--;
           }
           break;
         }