Fix race condition in docker-compose up.

Signed-off-by: Daniel Nephin <dnephin@gmail.com>

compose/cli/main.py

@@ -453,7 +453,7 @@ class TopLevelCommand(Command):
         service_names = options['SERVICE']
         timeout = float(options.get('--timeout') or DEFAULT_TIMEOUT)
 
-        project.up(
+        to_attach = project.up(
             service_names=service_names,
             start_deps=start_deps,
             allow_recreate=allow_recreate,
@@ -463,8 +463,6 @@ class TopLevelCommand(Command):
             timeout=timeout
         )
 
-        to_attach = [c for s in project.get_services(service_names) for c in s.containers()]
-
         if not detached:
             print("Attaching to", list_containers(to_attach))
             log_printer = LogPrinter(to_attach, attach_params={"logs": True}, monochrome=monochrome)