src/Pure/Tools/phabricator.scala

 
   final class API private(ssh_user: String, ssh_host: String, ssh_port: Int)
   {
     /* connection */
 
-    require(ssh_host.nonEmpty && ssh_port >= 0)
+    require(ssh_host.nonEmpty && ssh_port >= 0, "bad ssh host or port")
 
     private def ssh_user_prefix: String = SSH.user_prefix(ssh_user)
     private def ssh_port_suffix: String = SSH.port_suffix(ssh_port)
 
     override def toString: String = ssh_user_prefix + ssh_host + ssh_port_suffix

       short_name: String = "",  // unique name
       description: String = "",
       public: Boolean = false,
       vcs: API.VCS.Value = API.VCS.hg): API.Repository =
     {
-      require(name.nonEmpty)
+      require(name.nonEmpty, "bad repository name")
 
       val transactions =
         API.edits("vcs", vcs.toString) :::
         API.edits("name", name) :::
         API.opt_edits("callsign", proper_string(callsign)) :::