Rustdoc: cannot type "add_assign" into the search box

[ghost]

This is a really strange bug. It manifests in both Firefox and Chrome.

How to reproduce:

1. Go to https://doc.rust-lang.org/nightly/std/
2. Type add_assign into the search box.
3. Only add_ will show up in the box. The rest of the entered characters are ignored.

[hanna-kruppe]

Can't reproduce on Firefox 59.0.1 (64-Bit), Windows 10.

[sfackler]

Seems to work for me on Chrome in Windows 10.

[bluss]

I am at times having problems with typing s into the search box, and that happened when I tried to reproduce this bug as well (So you get add_aign). Browser Firefox 59.0.1, on Linux.

[ghost]

Ok, here's some more information.

If I type add_a and wait for two seconds until the search results show up, then I can continue typing ssign. It's all good.

But if I don't wait after typing add_a, and just continue typing s, then search results will never show up. The page is simply stuck in an odd state and I cannot type in any more letters.

The only way of "fixing" it seems to be by hitting backspace and waiting for the results to show up. After that I can type assign.

[kennytm]

Duplicate of #49075.