Patch up HTTP clients

cmd/syncthing/main.go

@@ -30,6 +30,7 @@ import (
 	"github.com/syncthing/syncthing/lib/config"
 	"github.com/syncthing/syncthing/lib/connections"
 	"github.com/syncthing/syncthing/lib/db"
+	"github.com/syncthing/syncthing/lib/dialer"
 	"github.com/syncthing/syncthing/lib/discover"
 	"github.com/syncthing/syncthing/lib/events"
 	"github.com/syncthing/syncthing/lib/logger"
@@ -432,6 +433,8 @@ func upgradeViaRest() error {
 	r.Header.Set("X-API-Key", cfg.GUI().APIKey)
 
 	tr := &http.Transport{
+		Dial:            dialer.Dial,
+		Proxy:           http.ProxyFromEnvironment,
 		TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
 	}
 	client := &http.Client{