Docker image does not build anymore

[tranfuga25s]

Summary of issue

Clone the repository and build the image, cannot build the app container

Steps to reproduce

Install a new repository using the command lines
./dcp up

Error appears as:

Reading state information...
E: Unable to locate package php7-fpm
E: Unable to locate package php7-cli                                                                                                                                       
E: Unable to locate package php7-xdebug                                                                                                                                    
E: Unable to locate package php7-pdo                                                                                                                                       
E: Unable to locate package php7-pdo-mysql                                                                                                                                 
E: Unable to locate package php7-pdo-pgsql                                                                                                                                 
E: Unable to locate package php7-sqlite3                                                                                                                                   
E: Unable to locate package php7-xml                                                                                                                                       
E: Unable to locate package php7-mbstring                                                                                                                                  
E: Unable to locate package php7-tokenizer                                                                                                                                 
E: Unable to locate package php7-zip                                                                                                                                       
E: Unable to locate package php7-mcrypt
E: Unable to locate package php7-gd
E: Unable to locate package php7-curl
E: Unable to locate package php7-soap
E: Unable to locate package php7-redis

[tranfuga25s]

Solution might be #815