Always do symbol unsubscribe on teardown

piker/ui/watchlist.py

@@ -391,6 +391,7 @@ async def _async_main(name, portal, tickers, brokermod, rate):
         "piker.brokers.core", 'start_quote_stream',
         broker=brokermod.name, tickers=tickers)
 
+    try:
         async with trio.open_nursery() as nursery:
             # get first quotes response
             log.debug("Waiting on first quote...")
@@ -459,6 +460,8 @@ async def _async_main(name, portal, tickers, brokermod, rate):
             # Trio-kivy entry point.
             await async_runTouchApp(widgets['root'])  # run kivy
             await agen.aclose()  # cancel aysnc gen call
+    finally:
+        # un-subscribe from symbols stream
         await portal.run(
             "piker.brokers.core", 'modify_quote_stream',
             broker=brokermod.name, tickers=[])