support 'from __future__ import absolute_import'

Cython/Compiler/ExprNodes.py

@@ -34,7 +34,7 @@ import Symtab
 import Options
 from Cython import Utils
 from Annotate import AnnotationItem
-
+from Cython.Compiler import Future
 from Cython.Debugging import print_call_chain
 from DebugFlags import debug_disposal_code, debug_temp_alloc, \
     debug_coercion
@@ -1933,7 +1933,8 @@ class ImportNode(ExprNode):
 
     def analyse_types(self, env):
         if self.level is None:
-            if env.directives['language_level'] < 3 or env.directives['py2_import']:
+            if (env.directives['py2_import'] or
+                Future.absolute_import not in env.global_scope().context.future_directives):
                 self.level = -1
             else:
                 self.level = 0

Cython/Compiler/Future.py

@@ -10,6 +10,7 @@ unicode_literals = _get_feature("unicode_literals")
 with_statement = _get_feature("with_statement")
 division = _get_feature("division")
 print_function = _get_feature("print_function")
+absolute_import = _get_feature("absolute_import")
 nested_scopes = _get_feature("nested_scopes")  # dummy
 generators = _get_feature("generators")  # dummy
 

Cython/Compiler/Main.py

@@ -81,9 +81,8 @@ class Context(object):
     def set_language_level(self, level):
         self.language_level = level
         if level >= 3:
-            from Future import print_function, unicode_literals
-            self.future_directives.add(print_function)
-            self.future_directives.add(unicode_literals)
+            from Future import print_function, unicode_literals, absolute_import
+            self.future_directives.update([print_function, unicode_literals, absolute_import])
             self.modules['builtins'] = self.modules['__builtin__']
 
     # pipeline creation functions can now be found in Pipeline.py