make sure to set pr split view (#4617)

Signed-off-by: Lanre Adelowo <yo@lanre.wtf>

routers/routes/routes.go

@@ -564,7 +564,7 @@ func RegisterRoutes(m *macaron.Macaron) {
 		}, reqRepoWriter, context.RepoRef(), context.CheckAnyUnit(models.UnitTypeIssues, models.UnitTypePullRequests))
 
 		m.Combo("/compare/*", repo.MustAllowPulls, repo.SetEditorconfigIfExists).
-			Get(repo.CompareAndPullRequest).
+			Get(repo.SetDiffViewStyle, repo.CompareAndPullRequest).
 			Post(bindIgnErr(auth.CreateIssueForm{}), repo.CompareAndPullRequestPost)
 
 		m.Group("", func() {