Define __file__ when we %edit a real file.

Closes gh-2765.

IPython/core/magics/code.py

@@ -28,6 +28,7 b' from IPython.core.oinspect import find_file, find_source_lines'
 from IPython.testing.skipdoctest import skip_doctest
 from IPython.utils import openpy
 from IPython.utils import py3compat
+from IPython.utils.contexts import preserve_keys
 from IPython.utils.io import file_read
 from IPython.utils.path import get_py_filename, unquote_filename
 from IPython.utils.warn import warn
@@ -513,6 +514,9 b' class CodeMagics(Magics):'
             print
         else:
             print 'done. Executing edited code...'
+            with preserve_keys(self.shell.user_ns, '__file__'):
+                if not is_temp:
+                    self.shell.user_ns['__file__'] = filename
             if 'r' in opts:    # Untranslated IPython code
                 self.shell.run_cell(file_read(filename),
                                                     store_history=False)