[pygobject] gitlab-ci: add Python 3.7.0b2 job

[Christoph Reiter <creiter src gnome org>]

commit 9b5a99c1243c2840c133645a5e6287d4186f89b5
Author: Christoph Reiter <reiter christoph gmail com>
Date:   Thu Mar 1 16:07:10 2018 +0100

    gitlab-ci: add Python 3.7.0b2 job

 .gitlab-ci.yml           | 5 +++++
 .gitlab-ci/Dockerfile    | 1 +
 .gitlab-ci/run-docker.sh | 2 ++
 3 files changed, 8 insertions(+)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index d6915e46..ce06132c 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -87,3 +87,8 @@ python3.6:
   variables:
     PYENV_VERSION: "3.6.4"
   <<: *defaults
+
+python3.7:
+  variables:
+    PYENV_VERSION: "3.7.0b2"
+  <<: *defaults
diff --git a/.gitlab-ci/Dockerfile b/.gitlab-ci/Dockerfile
index e7fde966..cd486a2d 100644
--- a/.gitlab-ci/Dockerfile
+++ b/.gitlab-ci/Dockerfile
@@ -43,5 +43,6 @@ RUN pyenv install 2.7.14
 RUN pyenv install 3.4.7
 RUN pyenv install 3.5.5
 RUN pyenv install 3.6.4
+RUN pyenv install 3.7.0b2
 
 ENV PATH="/usr/lib/ccache:${PATH}"
diff --git a/.gitlab-ci/run-docker.sh b/.gitlab-ci/run-docker.sh
index ec171120..0b3757fc 100755
--- a/.gitlab-ci/run-docker.sh
+++ b/.gitlab-ci/run-docker.sh
@@ -1,5 +1,7 @@
 #!/bin/bash
 
+set -e
+
 TAG="lazka/pygobject:pyenv"
 
 sudo docker build --build-arg HOST_USER_ID="$UID" --tag "${TAG}" \