Add --gerrit-unsafe-dont-check-for-dups.

java/com/google/copybara/git/GerritDestination.java

@@ -205,6 +205,11 @@ private String computeInternalHashTag(TransformResult result) {
 
     private Optional<ChangeInfo> findActiveChange(String hashTag)
         throws RepoException, ValidationException {
+      if (gerritOptions.unsafeDontCheckForDups) {
+        // --gerrit-unsafe-dont-check-for-dups: skip the REST query and behave as if no existing
+        // change was found.
+        return Optional.empty();
+      }
 
       console.progressFmt("Querying Gerrit ('%s') for active changes with hashtag '%s'",
           repoUrl, hashTag);

java/com/google/copybara/git/GerritOptions.java

@@ -89,6 +89,17 @@ public void validate(String name, String value) throws ParameterException {
       description = "Create a new change instead of trying to reuse an existing one.")
   protected boolean newChange = false;
 
+  @Parameter(
+      names = "--gerrit-unsafe-dont-check-for-dups",
+      description =
+          "UNSAFE: skip querying Gerrit (by the internal copybara hashtag) for an existing open"
+              + " change before creating one. Lets git.gerrit_destination run with no Gerrit REST"
+              + " call at all, e.g. against an ssh-only Gerrit URL. Cost: each run mints a fresh"
+              + " Change-Id, so re-running before a change is submitted _may_ create a duplicate"
+              + " change instead of a new patch set. Generated Change-Ids are stable so you"
+              + " might get lucky.")
+  protected boolean unsafeDontCheckForDups = false;
+
   @Parameter(names = "--gerrit-topic", description = "Gerrit topic to use")
   protected String gerritTopic = "";