E402: Add "if" statement to allowed keywords

Author: EricCousineau-TRI

pycodestyle.py

@@ -1067,7 +1067,8 @@ def is_string_literal(line):
             line = line[1:]
         return line and (line[0] == '"' or line[0] == "'")
 
-    allowed_keywords = ('try', 'except', 'else', 'finally', 'with')
+    allowed_keywords = (
+        'try', 'except', 'else', 'finally', 'with', 'if')
 
     if indent_level:  # Allow imports in conditional statement/function
         return

testsuite/E40.py

@@ -39,6 +39,11 @@
     warnings.filterwarnings("ignore", DeprecationWarning)
     import foo
 
+import bar
+#: Okay
+if False:
+    import foo
+
 import bar
 #: E402
 VERSION = '1.2.3'