Cache Jython installation.

.travis.yml

@@ -16,6 +16,7 @@ deploy:
 cache:
   directories:
   - $TRAVIS_BUILD_DIR/.tox/shared/.m2
+  - $HOME/jython
 
 python:
   - '2.6'

ci/before_install_jython.sh

@@ -1,7 +1,10 @@
 #!/bin/sh
 set -e
 
-JYTHON_JAR=$(${TRAVIS_BUILD_DIR}/ci/mvnget.sh "$JYTHON")
-java -jar ${JYTHON_JAR} -s -d $HOME/jython
+INST_DIR=$HOME/jython/jython-${JYTHON##*:}
+if [ ! -d "$INST_DIR" ]; then
+    JYTHON_JAR=$(${TRAVIS_BUILD_DIR}/ci/mvnget.sh "$JYTHON")
+    java -jar ${JYTHON_JAR} -s -d "$INST_DIR"
+fi
 mkdir -p $HOME/bin
-ln -s $HOME/jython/bin/jython $HOME/bin/
+ln -s "$INST_DIR"/bin/jython $HOME/bin/