title: command git finished with non-zero exit value 128
body: <p>When I migrate Android project from Eclipse to Android Studio, use travis ci to build the project, it has the following errors.</p>
  
  <blockquote>
    <p>FAILURE: Build failed with an exception.<br>
    * Where:<br>
    Build file '/home/travis/build/Logan676/seadroid/app/build.gradle' line: 20<br>
    * What went wrong:<br>
    A problem occurred evaluating project ':app'.<br>
    Process 'command 'git'' finished with non-zero exit value 128  </p>
  </blockquote>
  
  <p>the build.gradle file is</p>
  
  <pre><code>    buildscript {
          repositories {
              jcenter()
          }
          dependencies {
              classpath 'com.android.tools.build:gradle:0.13.0'
          }
      }
      apply plugin: 'com.android.application'
  
      repositories {
          jcenter()
      }
  
      /*
       * Gets the version name from the latest Git tag
       */
      def getVersionName = { -&gt;
          def stdout = new ByteArrayOutputStream()
          exec {
              // LINE 20 IS HERER!!!!!!!!!!!!!
              commandLine 'git', 'describe', '--tags' 
              standardOutput = stdout
          }
          return stdout.toString().trim()
      }
      def getVersionCode = { -&gt;
          def stdout = new ByteArrayOutputStream()
          exec {
              commandLine 'git', 'rev-list', '--count', "HEAD"
              standardOutput = stdout
          }
          return Integer.valueOf(stdout.toString().trim())
      }
  
  
      dependencies {
          compile 'com.android.support:support-v4:21.0.+'
          compile 'com.actionbarsherlock:actionbarsherlock:4.4.0@aar'
          compile 'com.inkapplications.viewpageindicator:library:2.4.3'
          compile 'com.github.kevinsawicki:http-request:5.6'
          compile 'commons-io:commons-io:2.4'
          compile 'com.google.guava:guava:18.0'
          compile 'com.nostra13.universalimageloader:universal-image-loader:1.9.3'
          compile project(':libraries:NewQuickAction')
          compile project(':libraries:MarkdownView')
          compile project(':libraries:PullToRefresh')
      }
  
      android {
          compileSdkVersion rootProject.ext.compileSdkVersion
          buildToolsVersion rootProject.ext.buildToolsVersion
  
          defaultConfig {
              minSdkVersion rootProject.ext.minSdkVersion
              targetSdkVersion rootProject.ext.targetSdkVersion
              versionCode getVersionCode()
              versionName getVersionName()
          }
  
          lintOptions {
              abortOnError false
          }
  
          signingConfigs {
              release {
                  // Signing code for manual signing
                  //storeFile file(System.console().readLine("\n\$ Enter keystore path: "))
                  //storePassword System.console().readPassword("\n\$ Enter keystore      password: ").toString()
                  //keyAlias System.console().readLine("\n\$ Enter key alias: ")
                  //keyPassword System.console().readPassword("\n\$ Enter key password:    ").toString()
              }
          }
  
          buildTypes {
              release {
                  //signingConfig signingConfigs.release
                  runProguard true
                  proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-project.txt'
              }
          }
      }
  </code></pre>
  
  <p>I guess it caused by not installed git error. But I don`t know how to fix it. Maybe it needs some script to automatically install git. So anyone can help me modify the Gradle file as showed above.</p>