Bump greenlet dependency.

Fixes #1627

.travis.yml

@@ -177,7 +177,7 @@ jobs:
         # First, the build dependencies (see setup.cfg)
         # so that we don't have to use build isolation and can better use the cache;
         # Note that we can't use -U for cffi and greenlet on PyPy.
-        - &build-gevent-deps pip install -U setuptools wheel twine && pip install -U 'faulthandler; python_version == "2.7" and platform_python_implementation == "CPython"' 'cffi;platform_python_implementation=="CPython"' 'cython>=3.0a5' 'greenlet;platform_python_implementation=="CPython" and python_version <= "3.8"' 'git+https://github.com/python-greenlet/greenlet.git#egg=greenlet ; platform_python_implementation == "CPython" and python_version >= "3.9.0b1"'
+        - &build-gevent-deps pip install -U setuptools wheel twine && pip install -U 'faulthandler; python_version == "2.7" and platform_python_implementation == "CPython"' 'cffi;platform_python_implementation=="CPython"' 'cython>=3.0a5' 'greenlet;platform_python_implementation=="CPython"'
         # Next, build the wheel *in place*. This helps ccache, and also lets us cache the configure
         # output (pip install uses a random temporary directory, making this difficult)
         - python setup.py bdist_wheel

deps/greenlet/greenlet.h

@@ -11,7 +11,7 @@
 extern "C" {
 #endif
 
-#define GREENLET_VERSION "0.4.14"
+#define GREENLET_VERSION "0.4.16"
 
 #if PY_VERSION_HEX >= 0x030700A3
 #  define GREENLET_USE_EXC_INFO

docs/changes/1627.bugfix

+Depend on greenlet >= 0.4.16. This is required for CPython 3.9 and 3.10a0.

pyproject.toml

@@ -22,12 +22,8 @@ requires = [
      # See version requirements in setup.py
      "cffi >= 1.12.3 ; platform_python_implementation == 'CPython'",
      # Python 3.7 requires at least 0.4.14, which is ABI incompatible with earlier
-     # releases. Python 3.9 and 3.10 require 0.4.16, which has not been released yet.
-     # Listing it here fails to find a distro on PyPI; and this setting won't accept
-     # git+https:// VCS urls, it seems. If we list it in dev-requirements.txt, we seem to
-     # get what we need.
-     "greenlet>=0.4.14 ; platform_python_implementation == 'CPython' and python_version <= '3.8'",
-     #"greenlet > 0.4.15 ; platform_python_implementation == 'CPython' and python_version >= '3.9.0b1'",
+     # releases. Python 3.9 and 3.10 require 0.4.16
+     "greenlet >= 0.4.16 ; platform_python_implementation == 'CPython'",
 ]
 
 [tool.towncrier]

setup.py

@@ -193,7 +193,7 @@ greenlet_requires = [
     # since we compile cython code that extends the greenlet object.
     # Binary compatibility would break if the greenlet struct changes.
     # (Which it did in 0.4.14 for Python 3.7)
-    'greenlet >= 0.4.14; platform_python_implementation=="CPython"',
+    'greenlet >= 0.4.16; platform_python_implementation=="CPython"',
 ]
 
 # Note that we don't add cffi to install_requires, it's