Add mercurial to the CI environment
Add mercurial to the CI environment

This seems to be needed by some Go packages

Fixes: #589

davidvossel/kubevirt,davidvossel/kubevirt,stu-gott/kubevirt,fabiand/kubevirt,kubevirt/kubevirt,davidvossel/kubevirt,fabiand/kubevirt,kubevirt/kubevirt,rmohr/kubevirt,stu-gott/kubevirt,rmohr/kubevirt,kubevirt/kubevirt,stu-gott/kubevirt,kubevirt/kubevirt,davidvossel/kubevirt,stu-gott/kubevirt