address review comments

- Cancel discarded response bodies before retrying so the underlying
  connection can be returned to the pool instead of being held open
  until the response is garbage collected.
- Stop asserting on the rejected error message in the network-error
  retry test; track rejection via a flag so the test isn't tied to
  fetch/MSW error strings.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Signed-off-by: Fredrik Adelöw <freben@spotify.com>

packages/integration/src/gitlab/GitLabIntegration.test.ts

@@ -370,15 +370,15 @@ describe('GitLabIntegration', () => {
 
       // Attach the catch handler before advancing timers so the in-flight
       // rejections don't surface as unhandled.
-      const caught = integration
-        .fetch('https://h.com/api/v4')
-        .catch((e: unknown) => e);
+      let didReject = false;
+      const settled = integration.fetch('https://h.com/api/v4').catch(() => {
+        didReject = true;
+      });
       await jest.advanceTimersByTimeAsync(100);
       await jest.advanceTimersByTimeAsync(200);
-      const error = await caught;
+      await settled;
 
-      expect(error).toBeTruthy();
-      expect(String(error)).toMatch(/fetch/i);
+      expect(didReject).toBe(true);
       expect(callCount).toBe(3); // initial + 2 retries
     });
   });

packages/integration/src/gitlab/GitLabIntegration.ts

@@ -140,6 +140,10 @@ export class GitLabIntegration implements ScmIntegration {
           ? parseInt(retryAfter, 10) * 1000
           : Math.min(100 * Math.pow(2, attempt - 1), 10000); // Exponential backoff, cap at 10 seconds
 
+        // Release the underlying connection so it can be reused, since we're
+        // about to discard this response in favor of a retry.
+        await response?.body?.cancel().catch(() => {});
+
         await sleep(delay, abortSignal);
       }
     };