WL#3232 mysqltest, enable --source $variables/<remaining_path_to_file>

 - Add test case for this already existing feature 

mysql-test/r/mysqltest.result

@@ -330,6 +330,7 @@ here is the sourced script
 
 In loop
 here is the sourced script
+here is the sourced script
 mysqltest: At line 1: Missing argument to sleep
 mysqltest: At line 1: Missing argument to real_sleep
 mysqltest: At line 1: Invalid argument to sleep "abc"

mysql-test/t/mysqltest.test

@@ -807,6 +807,10 @@ while ($num)
 }
 --enable_abort_on_error
 --enable_query_log
+
+# Test source $variable/<filename>
+--source $MYSQLTEST_VARDIR/tmp/sourced.inc
+
 --remove_file $MYSQLTEST_VARDIR/tmp/sourced.inc
 
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