Improve checkConflict

* Delete temporary RefSpec after checkConflict
* mergeguide use checkconflictInPullRequest instead of checkconflict

src/main/scala/util/ControlUtil.scala

@@ -3,6 +3,7 @@ package util
 import org.eclipse.jgit.api.Git
 import org.eclipse.jgit.revwalk.RevWalk
 import org.eclipse.jgit.treewalk.TreeWalk
+import org.eclipse.jgit.transport.RefSpec
 
 /**
  * Provides control facilities.
@@ -37,6 +38,17 @@ object ControlUtil {
   def using[T](treeWalk: TreeWalk)(f: TreeWalk => T): T =
     try f(treeWalk) finally treeWalk.release()
 
+
+  def withTmpRefSpec[T](ref: RefSpec, git: Git)(f: RefSpec => T): T = {
+    try {
+      f(ref)
+    } finally {
+      val refUpdate = git.getRepository.updateRef(ref.getDestination)
+      refUpdate.setForceUpdate(true)
+      refUpdate.delete()
+    }
+  }
+
   def executeIf(condition: => Boolean)(action: => Unit): Boolean =
     if(condition){
       action