Instead of using usermod, delete the users and create anew, so we can…

… use --no-log-init option. Without this option, users with very large UID numbers were experiencing docker build hangs, and filling up drives. See moby/moby#5419

dockerfiles/set-user-ids.sh

@@ -11,12 +11,17 @@ USER_NAME=$1
 USER_UID=$2
 WEB_UID=$3
 
-echo "$PREFIX Changing user '$USER_NAME' UID/GID to '$USER_UID'...
+echo "$PREFIX Recreating user '$USER_NAME' UID/GID to '$USER_UID'...
 "
-usermod -u $USER_UID $USER_NAME
-groupmod -g $USER_UID $USER_NAME
+userdel $USER_NAME
+chown $USER_UID:$USER_UID /var/$USER_NAME
+
+addgroup --gid $USER_UID $USER_NAME
+useradd --no-log-init --uid $USER_UID --gid $USER_UID --system --home-dir /var/$USER_NAME $USER_NAME
 
 echo "$PREFIX Changing user 'www-data' UID/GID to '$WEB_UID'...
 "
-usermod -u $WEB_UID www-data
-groupmod -g $WEB_UID www-data
+
+userdel www-data
+addgroup --gid $WEB_UID www-data
+useradd --no-log-init --uid $WEB_UID --gid $WEB_UID --system  www-data