hi there! i'm trying to follow the getting started to get a taste

i get an error when running boot --help at https://perun.io/guides/getting-started/#step-3-the-simplest-thing-possible-

$ boot --help
Retrieving maven-metadata.xml from 
Retrieving perun-0.4.2-20171117.211243-6.pom from  (7k)
Retrieving perun-0.4.2-20171117.211243-6.jar from  (26k)
                                                  Boot.main                    Boot.java:  257
                                                        ...                                   
                                              boot.App.main                     App.java:  491
                                           boot.App.runBoot                     App.java:  399
org.projectodd.shimdandy.impl.ClojureRuntimeShimImpl.invoke  ClojureRuntimeShimImpl.java:  150
org.projectodd.shimdandy.impl.ClojureRuntimeShimImpl.invoke  ClojureRuntimeShimImpl.java:  159
                                                        ...                                   
                                            boot.main/-main                     main.clj:  216
                                         boot.main/-main/fn                     main.clj:  216
                                   clojure.core/load-string                     core.clj: 3959
                                   clojure.core/load-reader                     core.clj: 3957
                                                        ...                                   
                                    boot.user$eval34.invoke                             :    8
                              boot.user$eval34.invokeStatic                             :    8
                                                        ...                                   
                                       clojure.core/require                     core.clj: 5796 (repeats 2 times)
                                         clojure.core/apply                     core.clj:  648
                                                        ...                                   
                                     clojure.core/load-libs                     core.clj: 5758
                                     clojure.core/load-libs                     core.clj: 5774
                                         clojure.core/apply                     core.clj:  648
                                                        ...                                   
                                      clojure.core/load-lib                     core.clj: 5717
                                      clojure.core/load-lib                     core.clj: 5755
                                         clojure.core/apply                     core.clj:  648
                                                        ...                                   
                                         clojure.core/refer                     core.clj: 4087
                                         clojure.core/refer                     core.clj: 4122
                                                        ...                                   
java.lang.IllegalStateException: trace already refers to: #'boot.util/trace in namespace: boot.user
     clojure.lang.ExceptionInfo: trace already refers to: #'boot.util/trace in namespace: boot.user
    line: 8

any idea how to fix this?

oh, never mind. it was the :refer :all when requiring io/perun in build.boot