Some time between the 2.0.4 and the 2.1.0 upgrade, Bootstrap broke in
a way such that clicking on a dropdown did not cause it to close.
Here's the bug thread about it:
https://github.com/twitter/bootstrap/issues/4497
I've implemented this workaround discussed there, though the bug is
fixed in 2.1.1, so when we upgrade this will go away (which is why I
only reluctantly tag it 'third', since the diff will not need to be
carried forward.)
(imported from commit f8d9cf65b33306a426d864c9b503bb3446614111)