Abort release builds if already re-queued

ros_buildfarm/templates/release/rpm/binarypkg_job.xml.em

@@ -66,6 +66,9 @@ but disabled since the package is blacklisted (or not whitelisted) in the config
 @(SNIPPET(
     'builder_system-groovy_check-free-disk-space',
 ))@
+@(SNIPPET(
+    'builder_system-groovy_check-for-re-queue',
+))@
 @(SNIPPET(
     'builder_shell_docker-info',
 ))@

ros_buildfarm/templates/snippet/builder_system-groovy_check-for-re-queue.xml.em

@@ -0,0 +1,26 @@
+@{
+# This is a workaround for ros-infrastructure/ros_buildfarm#475, which describes
+# a decade-old bug in Jenkins that results jobs getting built twice
+# unnecessarily.
+}@
+@(SNIPPET(
+  'builder_system-groovy',
+  command=
+"""// VERIFY THAT THIS PROJECT HAS NOT ALREADY BEEN RE-QUEUED
+
+println ""
+println "# BEGIN SECTION: Check for duplicate triggers"
+
+try {
+  project = Thread.currentThread().executable.project
+  if (project.isInQueue()) {
+    println "Another build of this project is already queued -> aborting build"
+    throw new InterruptedException()
+  }
+} finally {
+  println "# END SECTION"
+  println ""
+}
+""",
+  script_file=None,
+))@