pinned for v0.5.0 release

Author: heschlie

build.sh

@@ -7,7 +7,7 @@ apk -U add --virtual temp python-dev py-pip alpine-sdk python py-setuptools open
 
 # Install python dependencies
 pip install --upgrade pip
-pip install -r https://raw.githubusercontent.com/projectcalico/libcalico/master/build-requirements-frozen.txt
+pip install -r https://raw.githubusercontent.com/projectcalico/libcalico/v0.18.0/build-requirements-frozen.txt
 pip install git+https://github.com/projectcalico/libcalico.git
 pip install simplejson