Fix make docker_build_kitchen_terraform

[ivankorn]

make docker_build_kitchen_terraform fail with fixed image variable reported in #6

[11:50][user@host:~/workspace/google/terraform-google-memorystore]$ make docker_build_kitchen_terraform 
docker build -f build/docker/kitchen_terraform/Dockerfile \
	--build-arg BUILD_TERRAFORM_IMAGE="gcr.io/cloud-foundation-cicd/cft/terraform:0.11.10_216.0.0_1.19.1_0.1.10" \
	--build-arg BUILD_RUBY_VERSION="2.5.3" \
	-t gcr.io/cloud-foundation-cicd/cft/kitchen_terraform:0.11.10_216.0.0_1.19.1_0.1.10 .
Sending build context to Docker daemon  247.8kB
Step 1/19 : ARG BUILD_TERRAFORM_IMAGE
Step 2/19 : ARG BUILD_RUBY_VERSION
Step 3/19 : FROM $BUILD_TERRAFORM_IMAGE as cfkt_terraform
0.11.10_216.0.0_1.19.1_0.1.10: Pulling from cloud-foundation-cicd/cft/terraform
4fe2ade4980c: Already exists 
2c86f8f0cefb: Pull complete 
ba485c5601c3: Pull complete 
d71b7a06b4a2: Pull complete 
928dbb700809: Pull complete 
c28139f3914c: Pull complete 
b0d9a880bf74: Pull complete 
Digest: sha256:ffe66e9232b1f3f2c59a74e3b39a9940ba005b7a04ba5f8a8d5bcc982837d01d
Status: Downloaded newer image for gcr.io/cloud-foundation-cicd/cft/terraform:0.11.10_216.0.0_1.19.1_0.1.10
 ---> 5e3b0f936574
Step 4/19 : FROM ruby:$BUILD_RUBY_VERSION-alpine
2.5.3-alpine: Pulling from library/ruby
8e402f1a9c57: Pull complete 
3cf24f050bbd: Pull complete 
164ebf0a871b: Pull complete 
9f9c5a242d0f: Pull complete 
60703f3614f7: Pull complete 
Digest: sha256:7ebec247c056cca18bd28e0d5c143641280327bb88584d750e87c3fa53f8aa60
Status: Downloaded newer image for ruby:2.5.3-alpine
 ---> 52484dfcf9bc
Step 5/19 : RUN apk add --no-cache         bash         curl         git         g++         jq         make         musl-dev         python
 ---> Running in a83947f6a772
fetch http://dl-cdn.alpinelinux.org/alpine/v3.9/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.9/community/x86_64/APKINDEX.tar.gz
(1/27) Upgrading musl (1.1.20-r3 -> 1.1.20-r4)
(2/27) Installing bash (4.4.19-r1)
Executing bash-4.4.19-r1.post-install
(3/27) Installing nghttp2-libs (1.35.1-r0)
(4/27) Installing libssh2 (1.8.2-r0)
(5/27) Installing libcurl (7.64.0-r2)
(6/27) Installing curl (7.64.0-r2)
(7/27) Upgrading libstdc++ (8.2.0-r2 -> 8.3.0-r0)
(8/27) Installing binutils (2.31.1-r2)
(9/27) Installing isl (0.18-r0)
(10/27) Installing libgomp (8.3.0-r0)
(11/27) Installing libatomic (8.3.0-r0)
(12/27) Installing mpfr3 (3.1.5-r1)
(13/27) Installing mpc1 (1.0.3-r1)
(14/27) Installing gcc (8.3.0-r0)
(15/27) Installing musl-dev (1.1.20-r4)
(16/27) Installing libc-dev (0.7.1-r0)
(17/27) Installing g++ (8.3.0-r0)
(18/27) Installing expat (2.2.7-r0)
(19/27) Installing pcre2 (10.32-r1)
(20/27) Installing git (2.20.1-r0)
(21/27) Installing oniguruma (6.9.1-r0)
(22/27) Installing jq (1.6-r0)
(23/27) Upgrading musl-utils (1.1.20-r3 -> 1.1.20-r4)
(24/27) Installing make (4.2.1-r2)
(25/27) Installing libbz2 (1.0.6-r7)
(26/27) Installing sqlite-libs (3.28.0-r0)
(27/27) Installing python2 (2.7.16-r1)
Executing busybox-1.29.3-r10.trigger
OK: 232 MiB in 61 packages
Removing intermediate container a83947f6a772
 ---> 32730726d10c
Step 6/19 : SHELL ["/bin/bash", "-c"]
 ---> Running in e16eeb1753c4
Removing intermediate container e16eeb1753c4
 ---> b39e555db095
Step 7/19 : ENV APP_BASE_DIR="/cftk"
 ---> Running in 947a389256c9
Removing intermediate container 947a389256c9
 ---> e128bd2fe29b
Step 8/19 : COPY --from=cfkt_terraform $APP_BASE_DIR $APP_BASE_DIR
COPY failed: stat /var/lib/docker/btrfs/subvolumes/5d957a5330e47d3d4853ec2326dc853adc51068c4197f825d6920beac504ebc0/cftk: no such file or directory
make: *** [Makefile:109: docker_build_kitchen_terraform] Error 1