Update test/fpm_test/test_filesystem.f90

Co-authored-by: Laurence Kedward <[email protected]>

Author: freevryheid

test/fpm_test/test_filesystem.f90

@@ -140,6 +140,7 @@ subroutine check_mkdir(error, path)
         if (is_dir(path)) then
             call test_failed(error, &
                 "Directory path "//path//" already exists before its creation")
+            return
         end if
 
         ! Create directory