The 500 fixed in 71738b05fc revealed that attempting to access g.v at
all during an error handler can potentially cause its own error.
In particular, html_head L111 accessing v.themecolor errored because
we roll back the database session during 500 handling. There's no good
solution other than specifically not passing v to 500 error pages.
However, in the interest of failing fast and ensuring error handlers
always complete, we instead go back to the previous behavior of not
treating users as logged in for error pages.
Snakes
27506b36c2
