sometmes, status line does not get updated until a key is pressed.

[lucas-mior]

When scrolling C files, sometimes the status line tag won't be updated from the last function.
Say I stop in the middle of function a(), but the status line says b(). Then, if I press any key at all,
the status is updated correctly to a(), if I didn't move away from it. It seems to happens at random.

EDIT:
Further testing shows that if I wait between keypresses (say <C-d> (wait a second) <C-d>). Then the statusline updates correctly. So the bug only happens when moving around in a hurry.