fixup! Extract spec/std/http/spec_helper

spec/std/http/spec_helper.cr

@@ -19,12 +19,16 @@ end
 # 4. Ensures the server is closed.
 # 5. After returning from the block, it waits for the server to gracefully
 #    shut down before continuing execution in the current fiber.
+# 6. If the listening fiber raises an exception, it is rescued and re-reraised
+#    in the current fiber.
 def run_server(server)
-  server_done = Channel(Nil).new
+  server_done = Channel(Exception).new
 
   spawn do
     server.listen
-  ensure
+  rescue exc
+    server_done.send exc
+  else
     server_done.send nil
   end
 
@@ -34,6 +38,9 @@ def run_server(server)
     yield server_done
   ensure
     server.close unless server.closed?
-    server_done.receive
+
+    if exc = server_done.receive
+      raise exc
+    end
   end
 end