diff-all page does not refresh properly

after clicking one of the "Diff All" buttons, i almost always get the diff i previously viewed. i need to make a forced reload in the browser (ctrl-f5 in firefox) to get the right content.

i suspect that gerrit is sending bogus cachability information, in particular a constant ETag or something like that.

1. Open a new Safari tab/window
2. Browse to a change, for example http://codereview.qt-project.org/#change,7190
3. Press the "Diff All Unified" button, the diff for change 7190 is shown, as expected
4. Press the Back button, returning to change 7190
5. Browse to another change, like the dependent change http://codereview.qt-project.org/#change,7191
6. Press the "Diff All Unified" button, the diff for change 7190 is shown, NOT what is expected
7. Refresh the page with Command+R, the diff for change 7191 is shown.