Login as an alias gets cached

When I make an alias for /user/login (for example, I created /login for ease of use), and enable caching, the form submits to /login (makes sense), but when submitted, the page appears cached. When the page is refreshed (manually in the browser), a new, logged-in page appears. This may/may not be a path problem, but it is an important issue. I do not appear to have the same problem when accessing /user/login even with caching enabled.

This may not be a Path problem, but I need to find a fix for this issue, or caching is unusable. If someone would like to reassign this to Drupal main or a cache project, feel free.