Travis CI build failed “eval ./gradlew assemble ” failed

Доброго времени суток. Есть проект на github, есть необходимость поставить к этому проекту continious integration, с файлом конфигурации всё вроде бы в норме. Он приведен ниже:

language: java
dist: precise
sudo: required
before_script: chmod +x gradlew
before_cache: rm -f $HOME/.gradle/caches/modules-2/modules-2.lock
cache:
  directories:
-$HOME/.gradle/caches/
-$HOME/.gradle/wrapper/
 jdk: oraclejdk8
 script: ./gradlew clean build -i --continue
before_build: ./mvnw install -DskipTests=true -Dmaven.javadoc.skip=true -B -V
build:  ./mvnw test -B

В репозитории есть и ./mvnw, pom.xml и build.gradle. Но Travis-CI выдает в конце следующую ошибку:

$ export PATH=$JAVA_HOME/bin:$PATH
cache.1
Setting up build cache
$ export CASHER_DIR=$HOME/.casher
0.14s$ Installing caching utilities
0.00s
0.59sattempting to download cache archive
fetching master/cache-linux-precise-
e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855--jdk oraclejdk8.tgz
fetching master/cache--jdk-oraclejdk8.tgz
could not download cache
0.00s
0.45s adding /home/travis/build/optima5918/Demo/-/home/travis/.gradle/caches to cache
creating directory 
/home/travis/build/optima5918/Demo/-/home/travis/.gradle/caches
adding /home/travis/build/optima5918/Demo/-/home/travis/.gradle/wrapper to 
cache
creating directory 
/home/travis/build/optima5918/Demo/-/home/travis/.gradle/wrapper
$ java -Xmx32m -version
java version "1.8.0_121"
Java(TM) SE Runtime Environment (build 1.8.0_121-b13)
Java HotSpot(TM) 64-Bit Server VM (build 25.121-b13, mixed mode)
$ javac -J-Xmx32m -version
javac 1.8.0_121
3.01s$ ./gradlew assemble
/home/travis/.travis/job_stages: line 236: ./gradlew: Permission denied
The command "eval ./gradlew assemble " failed. Retrying, 2 of 3.
/home/travis/.travis/job_stages: line 236: ./gradlew: Permission denied
The command "eval ./gradlew assemble " failed. Retrying, 3 of 3.
/home/travis/.travis/job_stages: line 236: ./gradlew: Permission denied
The command "eval ./gradlew assemble " failed 3 times.
The command "./gradlew assemble" failed and exited with 126 during .

Подскажите пожалуйста: как исправить ошибку:

The command "eval ./gradlew assemble " failed. Retrying, 2 of 3.
/home/travis/.travis/job_stages: line 236: ./gradlew: Permission denied