apache2_switch_mpm: MPM prefork not found

Problem

Error thrown, when trying to install "apache2 libapache2-mod-php7.0 php-apcu" all together.

Ubuntu version: Ubuntu 14.04.5 LTS
php-apcu version: 5.1.17+4.0.11-1+ubuntu14.04.1+deb.sury.org+1

Steps to Reproduce

- Install docker
- Create Dockerfile

FROM ubuntu:trusty
ARG DEBIAN_FRONTEND=noninteractive

RUN apt-get -qq update
RUN apt-get install -y software-properties-common language-pack-en-base
RUN LC_ALL=en_US.UTF-8 apt-add-repository -y ppa:ondrej/php
RUN apt-get -qq update
RUN apt-get -y install \
     apache2 \
     libapache2-mod-php7.0 \
     php7.0 \
     php-apcu

- Run "docker build ."

Expected Result
No error

Actual Result
Error thrown

No module matches
apache2_switch_mpm: MPM prefork not found
libapache2-mod-php7.0: Could not switch to prefork MPM, not enabling PHP 7.0