Fix how pending after upstream headers appears

Previously we didn't differentiate this case from aborted downstream,
which resulted in very weird UX, where the request appeared as pending
the view list, but aborted when selected. This mainly applies to
long-polling streams, where headers come back but no body until events
arrive (e.g. ntfy.sh).

This will be fixed better in future body streaming changes (already done
in Mockttp, but not yet active in the UI) so this is just a quick fix
for now.

Author: pimterry

src/model/http/upstream-exchange.ts

@@ -164,9 +164,10 @@ export class UpstreamHttpExchange extends HttpExchangeViewBase implements HttpEx
         if (this.upstreamResponseData === 'aborted') {
             return 'aborted';
         } else if (downstreamRes === 'aborted' || !downstreamRes) {
-            // Downstream was aborted, so upstream data (if any) is all we have
+            // Downstream is aborted or pending, so upstream data (if any) is all we have
+
+            if (downstreamRes && !this.wasResponseTransformed) return 'aborted';
 
-            if (!this.wasResponseTransformed) return 'aborted';
             const { statusCode, statusMessage, rawHeaders, body } = this.upstreamResponseData as
                 Required<typeof this.upstreamResponseData>; // If downstream is aborted, upstream data is complete