Merge pull request #1729 from thaJeztah/18.09_backport_e2e_handle_alpine_bump

[18.09 backport] Fixes for e2e testing after Alpine bump

e2e/testdata/Dockerfile.connhelper-ssh

@@ -1,10 +1,8 @@
 FROM docker:test-dind
 RUN apk --no-cache add shadow openssh-server && \
   groupadd -f docker && \
-  useradd -m penguin && \
+  useradd --create-home --shell /bin/sh --password $(head -c32 /dev/urandom | base64) penguin && \
   usermod -aG docker penguin && \
-  usermod -p $(head -c32 /dev/urandom | base64) penguin && \
-  chsh -s /bin/sh penguin && \
   ssh-keygen -A
 # workaround: ssh session excludes /usr/local/bin from $PATH
 RUN  ln -s /usr/local/bin/docker /usr/bin/docker