Fix failing test mysql_client_test

Backported patch from 10.3 that allows one to remove short .frm files

sql/datadict.cc

@@ -72,33 +72,36 @@ Table_type dd_frm_type(THD *thd, char *path, LEX_CSTRING *engine_name,
   if ((file= mysql_file_open(key_file_frm, path, O_RDONLY | O_SHARE, MYF(0)))
       < 0)
     DBUG_RETURN(TABLE_TYPE_UNKNOWN);
-  error= mysql_file_read(file, (uchar*) header, sizeof(header), MYF(MY_NABP));
 
-  if (error)
+  /*
+    We return TABLE_TYPE_NORMAL if we can open the .frm file. This allows us
+    to drop a bad .frm file with DROP TABLE
+  */
+  type= TABLE_TYPE_NORMAL;
+
+  /*
+    Initialize engine name in case we are not able to find it out
+    The cast is safe, as engine_name->str points to a usable buffer.
+   */
+  if (engine_name)
+  {
+    engine_name->length= 0;
+    ((char*) (engine_name->str))[0]= 0;
+  }
+
+  if ((error= mysql_file_read(file, (uchar*) header, sizeof(header), MYF(MY_NABP))))
     goto err;
+
   if (!strncmp((char*) header, "TYPE=VIEW\n", 10))
   {
     type= TABLE_TYPE_VIEW;
     goto err;
   }
 
-  /*
-    We return TABLE_TYPE_NORMAL if we can read the .frm file. This allows us
-    to drop a bad .frm file with DROP TABLE
-  */
-  type= TABLE_TYPE_NORMAL;
-
   /* engine_name is 0 if we only want to know if table is view or not */
   if (!engine_name)
     goto err;
 
-  /*
-    Initialize engine name in case we are not able to find it out
-    The cast is safe, as engine_name->str points to a usable buffer.
-   */
-  engine_name->length= 0;
-  ((char*) (engine_name->str))[0]= 0;
-
   if (!is_binary_frm_header(header))
     goto err;