Defaults to User Defined Completion instead of OmniComplete

[reem]

Relevant bit of my vimrc:

if !exists('g:neocomplcache_omni_patterns')
    let g:neocomplcache_omni_patterns = {}
endif
let g:neocomplcache_omni_patterns.rust = '[(\.)(::)]'

When I go to type rust and get to a section which matches this pattern:

let v = Vec::

I get a tiny pause and:

-- User defined completion (^U^N^P) Pattern not found

If I then do <C-X><C-O> to manually trigger omnicomplete everything works, so I know that omnifunc is set and working. The only explanation is that neocomplecache is defaulting to use user completions rather than omnicompletion. Is there some setting I can change to change this?

[reem]

Reading some other issues, it looks like this is fixed if you use g:neocomplecache_force_omni_patterns instead of the same with force.