Bug: rebuildChannel releaseOutputDir can't use exist folder

[gengjiawen]

When releaseOutputDir is already exist in filesystem.
I get the following exception

* What went wrong:
Execution failed for task ':passenger:reBuildChannel'.
> java.lang.NullPointerException (no error message)

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

If releaseOutputDir doesn't exist, everything works fine.

[ltlovezh]

the code is:
public boolean isNeedRebuildReleaseApk() {
if (baseReleaseApk == null || !baseReleaseApk.exists() || !baseReleaseApk.isFile()) {
println("baseReleaseApk : ${baseReleaseApk} , it is not a valid file , so can not rebuild release channel apk");
return false
} else {
if (releaseOutputDir == null) {
throw new GradleException("baseReleaseApk : ${baseReleaseApk} is ok , so you should set a valid releaseOutputDir , or you can set baseReleaseApk = null")
}

        if (!releaseOutputDir.exists()) {
            releaseOutputDir.mkdirs()
        } else {
            // delete old apks
            releaseOutputDir.eachFile { file ->
                if (file.name.endsWith(".apk")) {
                    file.delete()
                }
            }
        }
        return true
    }
}

and I didn't encounter this problem