fixes for test_ssl on old 2.7

src/gevent/_sslgte279.py

@@ -306,6 +306,9 @@ class SSLSocket(socket):
                 raise ValueError("Read on closed or unwrapped SSL socket.")
             if len == 0:
                 return b'' if buffer is None else 0
+            if len < 0:
+                # This is handled natively in python 2.7.12+
+                raise ValueError("Negative read length")
             try:
                 if buffer is not None:
                     return self._sslobj.read(len, buffer)

src/greentest/patched_tests_setup.py

@@ -262,6 +262,13 @@ if sys.version_info[:3] <= (2, 7, 8):
         'test_httpservers.SimpleHTTPServerTestCase.test_get'
     ]
 
+if sys.version_info[:3] <= (2, 7, 11):
+
+    disabled_tests += [
+        # These were added/fixed in 2.7.12+
+        'test_ssl.ThreadedTests.test__https_verify_certificates',
+        'test_ssl.ThreadedTests.test__https_verify_envvar',
+    ]
 
 if sys.platform == 'darwin':
     disabled_tests += [