From 3115b125de234c96a5cd509594f60f72241f2379 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ville=20Skytt=C3=A4?= <ville.skytta@iki.fi>
Date: Sun, 11 Aug 2019 22:33:42 +0300
Subject: [PATCH 1/3] Type hint istr keys allowed in LooseHeaders

So one can use e.g. {hdrs.SOMETHING: ...} as headers.
---
 aiohttp/typedefs.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/aiohttp/typedefs.py b/aiohttp/typedefs.py
index d7c97a435dd..60b0a4c8156 100644
--- a/aiohttp/typedefs.py
+++ b/aiohttp/typedefs.py
@@ -12,7 +12,8 @@
     Union,
 )
 
-from multidict import CIMultiDict, CIMultiDictProxy, MultiDict, MultiDictProxy
+from multidict import (
+    CIMultiDict, CIMultiDictProxy, MultiDict, MultiDictProxy, istr)
 from yarl import URL
 
 DEFAULT_JSON_ENCODER = json.dumps
@@ -33,7 +34,8 @@
 Byteish = Union[bytes, bytearray, memoryview]
 JSONEncoder = Callable[[Any], str]
 JSONDecoder = Callable[[str], Any]
-LooseHeaders = Union[Mapping[str, str], _CIMultiDict, _CIMultiDictProxy]
+LooseHeaders = Union[Mapping[Union[str, istr], str], _CIMultiDict,
+                     _CIMultiDictProxy]
 RawHeaders = Tuple[Tuple[bytes, bytes], ...]
 StrOrURL = Union[str, URL]
 LooseCookies = Union[Iterable[Tuple[str, 'BaseCookie[str]']],

From 7a9e1a49a59cd3dfaf5d2098a3d7374086cbc441 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ville=20Skytt=C3=A4?= <ville.skytta@iki.fi>
Date: Wed, 14 Aug 2019 16:50:18 +0300
Subject: [PATCH 2/3] isort aiohttp/typedefs imports

---
 aiohttp/typedefs.py | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/aiohttp/typedefs.py b/aiohttp/typedefs.py
index 60b0a4c8156..3c42f6abe30 100644
--- a/aiohttp/typedefs.py
+++ b/aiohttp/typedefs.py
@@ -13,7 +13,12 @@
 )
 
 from multidict import (
-    CIMultiDict, CIMultiDictProxy, MultiDict, MultiDictProxy, istr)
+    CIMultiDict,
+    CIMultiDictProxy,
+    MultiDict,
+    MultiDictProxy,
+    istr,
+)
 from yarl import URL
 
 DEFAULT_JSON_ENCODER = json.dumps

From c936b324823f773cc437f3ba70774973884b8e03 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ville=20Skytt=C3=A4?= <ville.skytta@iki.fi>
Date: Wed, 14 Aug 2019 16:51:42 +0300
Subject: [PATCH 3/3] Add CHANGES entry for #3976

---
 CHANGES/3976.bugfix | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 CHANGES/3976.bugfix

diff --git a/CHANGES/3976.bugfix b/CHANGES/3976.bugfix
new file mode 100644
index 00000000000..4e567ff3a11
--- /dev/null
+++ b/CHANGES/3976.bugfix
@@ -0,0 +1 @@
+Accept istr keys in LooseHeaders type hints.