fixed：同一方向pullrequest不允许存在

app/controllers/api/v1/projects/pulls/pulls_controller.rb

@@ -14,11 +14,19 @@ class Api::V1::Projects::Pulls::PullsController < Api::V1::BaseController
   end
 
   def reopen
-    @result_object = Api::V1::Projects::Pulls::ReopenService.call(@project, @pull_request, current_user)
-    if @result_object
-      render_ok
+    can_merge = @project&.pull_requests.where(head: @pull_request.head, base: @pull_request.base, status: 0, is_original: @pull_request.is_original, fork_project_id: @pull_request.fork_project_id)
+    if can_merge.present?
+      render json: {
+        status: -2,
+        message: "在这些分支之间的合并请求已存在：<a href='/#{@project.owner.login}/#{@project.identifier}/pulls/#{can_merge.first.id}''>#{can_merge.first.try(:title)}</a>",
+      }
     else
-      render_error("合并请求重新打开失败！")
+      @result_object = Api::V1::Projects::Pulls::ReopenService.call(@project, @pull_request, current_user)
+      if @result_object
+        render_ok
+      else
+        render_error("合并请求重新打开失败！")
+      end
     end
   end