[calico] Perform cleanup before building calico/cni

Since we modify 'glide.lock' file manually to fetch
downstream libcalico-go into 'vendor' directory,
git reports that repository state is 'dirty'. Reset
all changes before starting binary and image build
in order to get clean versions.

Change-Id: I266c793a6c0fddbf09dc1e8aa1157a86da603b17
diff --git a/src/com/mirantis/mcp/Calico.groovy b/src/com/mirantis/mcp/Calico.groovy
index 834ccd8..51826c2 100644
--- a/src/com/mirantis/mcp/Calico.groovy
+++ b/src/com/mirantis/mcp/Calico.groovy
@@ -374,6 +374,9 @@
     writeFile file: glideLockFilePath, text: common.dumpYAML(glideMap)
 
     sh "LIBCALICOGO_PATH=${libcalicogo_path} make vendor"
+    // need this to reset glide.lock changes (vendor dir is already compiled)
+    // otherwise binaries will be versioned with '-dirty' suffix
+    sh "git checkout ."
   }
 }