Hi, first of all, I know too little about mpm install policies on Debian. But my guess is that the dependency of mpm-itk on mpm-prefork should be hardcoded in the postinst script, as a sequence of steps that disable the conflicting mpm's and then proceed to a2enmod mpm_itk.
If enabling the installed module is not a mandatory policy, then just delete the enabling line. People enabling mpm_itk (other than the default mpm_event) know what they are doing and will manually enable it anyway.
Tomás Cohen Arazi
Prosecretaría de Informática
Universidad Nacional de Córdoba
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