pr-pull: fix PRs conflicting with themselves

https://github.com/Homebrew/homebrew-core/pull/106755#issuecomment-1206460655

Library/Homebrew/dev-cmd/pr-pull.rb

@@ -373,6 +373,8 @@ module Homebrew
       "org:#{user}", repo: repo, state: "open", label: "\"no long build conflict\""
     ).each_with_object({}) do |long_build_pr, hash|
       number = long_build_pr["number"]
+      next if number == pr
+
       GitHub.get_pull_request_changed_files("#{user}/#{repo}", number).each do |file|
         key = file["filename"]
         hash[key] ||= []