gradle-git：即使没有冲突，合并也会失败

Question

我正在使用gradle-git。我已经定义了两个任务如下：

PrepareTask.groovy

class PrepareTask extends DefaultTask {
  public String branch

  private Grgit git

  @TaskAction
  public void executeTask(){
    try {
      git = Grgit.open(dir: project.rootProject.projectDir)
    } catch (RepositoryNotFoundException e) {
      println("Git is not available in this project.")
    }
    if (git){
      def currentBranch = git.branch.getCurrent().getName()
      if (currentBranch != branch){
        git.checkout(branch: branch, createBranch: true)
      }
    }
  }
}

CommitTask.groovy

class CommitTask extends DefaultTask {
  public String prev_branch
  public String message = "committing changes"

  private Grgit git

  @TaskAction
  public void executeTask(){
    try {
      git = Grgit.open(dir: project.rootProject.projectDir)
    } catch (RepositoryNotFoundException e) {
      println("Git is not available in this project.")
    }

    if (git){
      git.add(patterns: ['.'])
      def commit = git.commit(message: message, all: true)
      if (prev_branch){
        def branch = git.branch.getCurrent().getName()
        git.checkout(branch: prev_branch, createBranch: false)
        git.merge(head: branch, mode: MergeOp.Mode.CREATE_COMMIT, message: "merging")
      }
    }
  }
}

我在gradle中有一个updateSource任务工作正常，我在 build.gradle 中设置了以下内容：

task prepare(type: PrepareTask){
  branch = 'changes-branch'
}

task commit(type: CommitTask){
  prev_branch = 'current-branch'
}

updateSource.dependsOn prepare
updateSource.finalizedBy commit

一切都在执行，新分支被创建和检出，源代码得到更新和提交，然后原始分支再次被检出。但是当任务尝试合并分支时，它会失败：

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':commit'.
> Problem merging.

添加--stacktrace选项会显示：

* Exception is:
org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':commit'.
        ...
Caused by: org.ajoberstar.grgit.exception.GrgitException: Problem merging.
        ...
Caused by: org.eclipse.jgit.api.errors.CheckoutConflictException: Checkout conflict with files:

但由于两个原因，这没有任何意义。结账很顺利，2。我从一个干净的分支开始。