Warn on Python 2.7

news/6148.removal

@@ -0,0 +1,2 @@
+Start printing a warning for Python 2.7 to warn of impending Python 2.7 End-of-life and
+prompt users to start migrating to Python 3.

src/pip/_internal/cli/base_command.py

@@ -143,6 +143,15 @@ def main(self, args):
                 replacement=None,
                 gone_in='19.2',
             )
+        elif sys.version_info[:2] == (2, 7):
+            deprecated(
+                "Python 2.7 will reach the end of its life on January 1st, "
+                "2020. Please upgrade your Python as Python 2.7 won't be "
+                "maintained after that date. A future version of pip will "
+                "drop support for Python 2.7.",
+                replacement=None,
+                gone_in=None,
+            )
 
         # TODO: Try to get these passing down from the command?
         #       without resorting to os.environ to hold these.

tests/conftest.py

@@ -349,4 +349,4 @@ def in_memory_pip():
 @pytest.fixture
 def deprecated_python():
     """Used to indicate wheither pip deprecated this python version"""
-    return sys.version_info[:2] == (3, 4)
+    return sys.version_info[:2] in [(3, 4), (2, 7)]