fix: remove artificial delay for PR update (#7773)

- I was not able to find a reasoning in the pull request (https://github.com/go-gitea/gitea/pull/9784) for the existence of this `time.Sleep`. The best I could come up with during manual testing is that there's a brief moment where 'this pull request is missing fork information' is shown, this was caused by an incorrect condition.
- Added integration test.

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/7773
Reviewed-by: 0ko <0ko@noreply.codeberg.org>
Reviewed-by: Otto <otto@codeberg.org>
Co-authored-by: Gusted <postmaster@gusted.xyz>
Co-committed-by: Gusted <postmaster@gusted.xyz>

routers/web/repo/pull.go

@@ -14,7 +14,6 @@ import (
 	"net/url"
 	"strconv"
 	"strings"
-	"time"
 
 	"forgejo.org/models"
 	activities_model "forgejo.org/models/activities"
@@ -728,7 +727,7 @@ func PrepareViewPullInfo(ctx *context.Context, issue *issues_model.Issue) *git.C
 	ctx.Data["HeadBranchCommitID"] = headBranchSha
 	ctx.Data["PullHeadCommitID"] = sha
 
-	if pull.HeadRepo == nil || !headBranchExist || (!pull.Issue.IsClosed && (headBranchSha != sha)) {
+	if pull.HeadRepo == nil || !headBranchExist || (!pull.Issue.IsClosed && !pull.IsChecking() && (headBranchSha != sha)) {
 		ctx.Data["IsPullRequestBroken"] = true
 		if pull.IsSameRepo() {
 			ctx.Data["HeadTarget"] = pull.HeadBranch
@@ -1208,8 +1207,6 @@ func UpdatePullRequest(ctx *context.Context) {
 		return
 	}
 
-	time.Sleep(1 * time.Second)
-
 	ctx.Flash.Success(ctx.Tr("repo.pulls.update_branch_success"))
 	ctx.Redirect(issue.Link())
 }