test_gdbm.rb: typo

* test/gdbm/test_gdbm.rb (teardown): fix instance variable name.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@52488 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/gdbm/test_gdbm.rb

@@ -68,7 +68,7 @@ if defined? GDBM
       begin
         FileUtils.remove_entry_secure @tmpdir
       rescue
-        system("fuser", *Dir.entries(@tmpdir).grep(/\A(?!\.\.?\z)/), chdir: @chdir)
+        system("fuser", *Dir.entries(@tmpdir).grep(/\A(?!\.\.?\z)/), chdir: @tmpdir)
       else
         return
       end