[3.5.2] Show a FutureWarning for Python 3.5.0-3.5.2

Bug: T286867
Change-Id: I5c2d9e04a1cc4e571389690b2ddd44e00a6b0bfc
---
M pywikibot/__init__.py
1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/pywikibot/__init__.py b/pywikibot/__init__.py
index 9e92d0c..a8493d5 100644
--- a/pywikibot/__init__.py
+++ b/pywikibot/__init__.py
@@ -69,7 +69,7 @@
 )
 from pywikibot.tools import classproperty
 from pywikibot.tools import deprecate_arg as _deprecate_arg
-from pywikibot.tools import normalize_username
+from pywikibot.tools import normalize_username, PYTHON_VERSION
 from pywikibot.tools.formatter import color_format
 
 
@@ -103,6 +103,15 @@
     argvu = []  # type: List[str]
 
 
+if PYTHON_VERSION < (3, 5, 3):
+    warn("""
+Python {version} will be dropped with release 7.0 soon.
+It is recommended to use Python 3.5.3 or above.
+See T286867 for further information.
+""".format(version=sys.version.split(maxsplit=1)[0]),
+         FutureWarning)  # probably adjust the line no in utils.execute()
+
+
 class Timestamp(datetime.datetime):
 
     """Class for handling MediaWiki timestamps.

