sslutil: drop support for clients of sslutil specifying a TLS version

We really just want to support the newest thing possible, so we may as
well consolidate that knowledge into this module. Right now this
doesn't change any behavior, but a future change will fix the defaults
for Python 2.7.9 so we can use slightly better defaults there (which
is the only place it's possible at the moment.)

mercurial/sslutil.py

@@ -18,10 +18,9 b' try:'
     try:
         ssl_context = ssl.SSLContext
 
-        def ssl_wrap_socket(sock, keyfile, certfile, ssl_version=PROTOCOL_TLSv1,
-                            cert_reqs=ssl.CERT_NONE, ca_certs=None,
-                            serverhostname=None):
-            sslcontext = ssl.SSLContext(ssl_version)
+        def ssl_wrap_socket(sock, keyfile, certfile, cert_reqs=ssl.CERT_NONE,
+                            ca_certs=None, serverhostname=None):
+            sslcontext = ssl.SSLContext(PROTOCOL_TLSv1)
             if certfile is not None:
                 sslcontext.load_cert_chain(certfile, keyfile)
             sslcontext.verify_mode = cert_reqs
@@ -37,12 +36,11 b' try:'
                 raise util.Abort(_('ssl connection failed'))
             return sslsocket
     except AttributeError:
-        def ssl_wrap_socket(sock, keyfile, certfile, ssl_version=PROTOCOL_TLSv1,
-                            cert_reqs=ssl.CERT_NONE, ca_certs=None,
-                            serverhostname=None):
+        def ssl_wrap_socket(sock, keyfile, certfile, cert_reqs=ssl.CERT_NONE,
+                            ca_certs=None, serverhostname=None):
             sslsocket = ssl.wrap_socket(sock, keyfile, certfile,
                                         cert_reqs=cert_reqs, ca_certs=ca_certs,
-                                        ssl_version=ssl_version)
+                                        ssl_version=PROTOCOL_TLSv1)
             # check if wrap_socket failed silently because socket had been
             # closed
             # - see http://bugs.python.org/issue13721
@@ -56,9 +54,8 b' except ImportError:'
 
     import socket, httplib
 
-    def ssl_wrap_socket(sock, keyfile, certfile, ssl_version=PROTOCOL_TLSv1,
-                        cert_reqs=CERT_REQUIRED, ca_certs=None,
-                        serverhostname=None):
+    def ssl_wrap_socket(sock, keyfile, certfile, cert_reqs=CERT_REQUIRED,
+                        ca_certs=None, serverhostname=None):
         if not util.safehasattr(socket, 'ssl'):
             raise util.Abort(_('Python SSL support not found'))
         if ca_certs:
@@ -126,8 +123,7 b' def _plainapplepython():'
             exe.startswith('/system/library/frameworks/python.framework/'))
 
 def sslkwargs(ui, host):
-    kws = {'ssl_version': PROTOCOL_TLSv1,
-           }
+    kws = {}
     hostfingerprint = ui.config('hostfingerprints', host)
     if hostfingerprint:
         return kws