General :: Handling Wordbreaks In Bash Completion?

I am writing completion function for one PHP framework called symfony. It has command line interface with syntax:

Code:

symfony [options] [namespace:]action

I want to make action be autocompletable. The function is simplest so far:

Code:

function _symfony_commands()
{
[ -r "cache/completion/.sf" ] && cat cache/completion/.sf
}

[code]....

But, if there is : symbol which separate namespace from action problems coming:

symfony doct[TAB]
will be completed to
symfony doctrine:

But nothing happens if you want complete after : symbol. I've found out that for readline there is three words because it splits line with $COMP_WORDBREAKS

Code:

$ echo $COMP_WORDBREAKS
"'><=;|&(:

I played with $COMP_WORDS array and tried every thought I had to make it work, but failed.
What I should do to escape colon and make readline consider it as one word? Or there is way perhaps to workaround it?