Revert "Allow running this repo as a pre-commit hook"

This reverts commit 9d64d78.

Author: koalaman

.dockerignore

@@ -1,3 +1,6 @@
-dist
-dist-newstyle
-.git
+*
+!LICENSE
+!Setup.hs
+!ShellCheck.cabal
+!shellcheck.hs
+!src

.pre-commit-hooks.yaml

@@ -1,9 +1,6 @@
 #!/bin/bash
 # This script runs 'buildtest' on each of several distros
 # via Docker.
-
-# shellcheck disable=SC2016
-
 set -o pipefail
 
 exec 3>&1 4>&2
@@ -35,33 +32,6 @@ echo "Logging to $log" >&3
 exec >> "$log" 2>&1
 
 final=0
-
-echo "Trying to build pre-commit docker image"
-if ! docker build --tag precommit .
-then
-  final=1
-  echo "pre-commit image failed to build"
-else
-  if printf '%s\n' '#!/bin/sh' 'echo $1' | docker run -i precommit -
-  then
-    final=1
-    echo "pre-commit image succeeds with incorrect example"
-  fi
-
-  if ! printf '%s\n' '#!/bin/sh' 'echo "$1"' | docker run -i precommit -
-  then
-    final=1
-    echo "pre-commit image fails with correct example"
-  fi
-fi
-
-if [[ $final -ne 0 ]]
-then
-  echo >&3 "pre-commit image failure, see log"
-else
-  echo >&3 "pre-commit image succeeded"
-fi
-
 while read -r distro setup
 do
   [[ "$distro" = "#"* || -z "$distro" ]] && continue