Merge branch 'master' into use-unasync-for-tests

diff --cc httpx/_client.py
index bbeef7b522a71b84291ecbfa7572c13391d5814e,13cd9336732a0854dae25b53b34e4b2e749b5897..17a71df8b4658f2aba6331c89ddf08e00ac8b6b2
--- 1/httpx/_client.py
--- 2/httpx/_client.py
+++ b/httpx/_client.py
@@@ -1721,9 -1721,9 +1721,9 @@@ class AsyncClient(BaseClient)
          transport = self._transport_for_url(request.url)
          start = time.perf_counter()
  
 -        if not isinstance(request.stream, AsyncByteStream):
 +        if not isinstance(request.stream, AsyncByteStream):  # pragma: no cover
              raise RuntimeError(
-                 "Attempted to send an sync request with an AsyncClient instance."
+                 "Attempted to send a sync request with an AsyncClient instance."
              )
  
          with request_context(request=request):