FIX opendevstack#1038 Helm deployment issues with custom chartDir option

This will bail out if the repository is ambigious about the deployment descriptor.

It will fail if:

* there is no deployment descriptor
* there is more than one deployment descriptor

For a successfull release to happen, developers are required to "clean" their repository of unrelated deployment desciptors that could interfere with the current version.

src/org/ods/orchestration/phases/DeployOdsComponent.groovy

@@ -127,11 +127,14 @@ class DeployOdsComponent {
             }
         }
     }
+
+    // FIXME: This method does not support multiple deployment descriptors.
     @TypeChecked(TypeCheckingMode.SKIP)
     private String computeStartDir() {
         List<File> files = steps.findFiles(glob: "**/${DeploymentDescriptor.FILE_NAME}")
         logger.debug("DeploymentDescriptors: ${files}")
-        if (!files || files.size() == 0) {
+        // If we find anything but _exactly_ one deployment descriptor, we fail.
+        if (!files || files.size() != 1) {
             throw new RuntimeException("Error: Could not determine starting directory. " +
                 "Neither of [chart, openshift, openshift-exported] found.")
         } else {