Keep already-packaged lein off the classpath in bin/pkg-lein.

bin/lein-pkg

@@ -83,12 +83,17 @@ lucene-memory maven-ant-tasks maven-artifact maven-artifact-manager \
 maven-error-diagnostics maven-model maven-settings maven-project maven-profile \
 maven-repository-metadata plexus-container-default-alpha plexus-interpolation \
 plexus-utils wagon-file wagon-http-lightweight wagon-http-shared wagon-provider-api \
-xml-apis lucene-core lucene-highlighter clucy robert-hooke lancet leiningen
+xml-apis lucene-core lucene-highlighter clucy robert-hooke lancet \
 backport-util-concurrent" # NFI why that last one is necessary
 for JAR in $SHARE_JARS; do
     CLASSPATH="$CLASSPATH":"/usr/share/java/$JAR.jar"
 done
 
+# Keep already-packaged Leiningen jar off the classpath during packaging.
+if [ ! -r src/leiningen/core.clj ]; then
+    CLASSPATH="$CLASSPATH":/usr/share/java/leiningen-$LEIN_VERSION.jar
+fi
+
 if [ $DEBUG ]; then
     echo $CLASSPATH
     echo $CLOJURE_JAR
@@ -113,7 +118,7 @@ if [ "$1" = "trampoline" ]; then
         if [ -r $TRAMPOLINE_FILE ]; then
             TRAMPOLINE="$(cat $TRAMPOLINE_FILE)"
             rm $TRAMPOLINE_FILE
-            exec sh -c "exec $TRAMPOLINE"
+            exec sh -c "TRAMPOLINE"
         fi
 else
         exec $RLWRAP $JAVA_CMD -Xbootclasspath/a:"$CLOJURE_JAR" -client $JVM_OPTS \