bug#20329: 25.0.50; Loading semantic breaks imenu

[Andreas Politz]

emacs -Q foo.py

(require 'semantic)
(normal-mode)
(call-interactively 'imenu)
  
=> (user-error "No items suitable for an index found in this buffer")

Merely loading semantic should not modify imenu-create-index-function in
all sorts of buffers.  It is also not so easy to get rid of it again.
One would have to either remove the semantic function from the various
mode hooks or install another function which runs *after* semantic's and
which would reinstall the regular imenu-create-index-function.

-ap