Android Studio自动更新app.iml支持libs到'alpha'版本

Question

为什么Android Studio 1.5.1（稳定版）会自动更新我的app.iml文件以使用Alpha支持库？

我的build.gradle：

apply plugin: 'com.android.application'

android {
    compileSdkVersion 22
    buildToolsVersion "22.0.1"

    defaultConfig {
        applicationId "my.app.id"
        minSdkVersion 15
        targetSdkVersion 22
        versionCode 5
        versionName "1.0.4"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}
repositories {
    maven { url 'https://github.com/8tory/parse-android-sdk.m2/raw/master/' }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:22.1'
    compile 'com.android.support:support-v4:22.1'
    compile 'com.android.support:recyclerview-v7:22.1'
}