I occasionally find myself pressing escape to exit a menu choice in mu4e
and it's a bit unfortunate that nothing happens. As best I could tell,
since this is a C call, none of the keymaps are checked for
`(keyboard-quit)' so we need to explicitly check for ESC here
This was previously fixed in 02b5bc805c
but was inadvertently removed in
0354fa4fac, so more detail was added to
the comment.
91464002b8