We need `libssl-dev`, and Sury provides a newer version than Debian.

debian/jessie/setup.sh

@@ -2,6 +2,24 @@
 
 echo "deb http://security.debian.org/ jessie/updates main" >> /etc/apt/sources.list
 
-apt-get update
-apt-get -y --install-suggests install git dh-make build-essential autoconf autotools-dev libpcre3 libpcre3-dev libz-dev shellcheck
+apt-get -y install \
+    apt-transport-https \
+    lsb-release \
+    ca-certificates \
+    curl
+curl -ssL -o /etc/apt/trusted.gpg.d/php.gpg https://packages.sury.org/php/apt.gpg
+sh -c 'echo "deb https://packages.sury.org/php/ $(lsb_release -sc) main" > /etc/apt/sources.list.d/php.list'
 
+apt-get update
+apt-get -y --install-suggests install \
+    git \
+    dh-make \
+    build-essential \
+    autoconf \
+    autotools-dev \
+    libpcre3 \
+    libpcre3-dev \
+    libz-dev \
+    shellcheck \
+    gnupg \
+    libssl-dev