Add conditional dependency on enum34 for Python 2.7

Author: tleonhardt

docs/requirements.txt

@@ -2,3 +2,5 @@ pyparsing
 six
 pyperclip
 contextlib2
+enum34
+subprocess32

setup.py

@@ -71,6 +71,8 @@
     ":sys_platform=='win32'": ['pyreadline'],
     # Python 3.4 and earlier require contextlib2 for temporarily redirecting stderr and stdout
     ":python_version<'3.5'": ['contextlib2'],
+    # Python 3.3 and earlier require enum34 backport of enum module from Python 3.4
+    ":python_version<'3.4'": ['enum34'],
     # Python 2.7 also requires subprocess32
     ":python_version<'3.0'": ['subprocess32'],
 }
@@ -81,6 +83,8 @@
         INSTALL_REQUIRES.append('pyreadline')
     if sys.version_info < (3, 5):
         INSTALL_REQUIRES.append('contextlib2')
+    if sys.version_info < (3, 4):
+        INSTALL_REQUIRES.append('enum34')
     if sys.version_info < (3, 0):
         INSTALL_REQUIRES.append('subprocess32')
 

tox.ini

@@ -12,6 +12,7 @@ setenv =
 [testenv:py27]
 deps =
   codecov
+  enum34
   mock
   pyparsing
   pyperclip
@@ -28,6 +29,7 @@ commands =
 [testenv:py27-win]
 deps =
   codecov
+  enum34
   mock
   pyparsing
   pyperclip