Docker image needs to include zlib-static

Author: snoyberg

stack.yaml

@@ -5,7 +5,8 @@ packages:
 
 docker:
   enable: false
-  repo: fpco/alpine-haskell-stack:8.10.4
+  #repo: fpco/alpine-haskell-stack:8.10.4
+  repo: fpco/alpine-haskell-stack@sha256:1024fe4b3b082a8df64d00e8563b3151220ed90af09604a8f7e1d44040500c30
 
 nix:
   # --nix on the command-line to enable.