'Search or filter results...' input unreliable, non-intuitive

If you go to the issue index https://gitlab.com/gitlab-org/gitlab-ce/issues and type something into the 'Search or filter results...' input and submit, you get search results.

If you again click the 'Search or filter results...' input, you might get an ordinary input behavior (where you can, for example, CTRL+A to select all) once, but if you click elsewhere and back again, the former query is turned into some block that you have to backspace to get access to, & a select all keyboard shortcut will not work.

I can see how this grouping might be useful & desired by some (maybe some more visual indication it has happened, though? Borders perhaps?), but not why the first click yields normal input behavior and subsequent ones yield this other behavior.