Python 2.6: add explicit requirement for "Pillow < 4.0"

I pushed Pillow 5.1 to MediaDrops "pypi". That version does not support Python 2.6 anymore but we also provide the old Pillow 3.4.2 for Python 2.6 users(I guess mostly CentOS 6/RHEL 6).
mediadrop · Apr 10, 2018 · a82e41e · a82e41e
1 parent acf5488
commit a82e41e
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/requirements.py26.txt b/requirements.py26.txt
@@ -1,2 +1,4 @@
 --index-url=https://static.mediadrop.video/dependencies/dev/
 importlib
+# Pillow 4.0 dropped support for Python 2.6
+Pillow < 4.0