E402: Add "elif" statement to allowed keywords

Author: EricCousineau-TRI

pycodestyle.py

@@ -1068,7 +1068,7 @@ def is_string_literal(line):
         return line and (line[0] == '"' or line[0] == "'")
 
     allowed_keywords = (
-        'try', 'except', 'else', 'finally', 'with', 'if')
+        'try', 'except', 'else', 'finally', 'with', 'if', 'elif')
 
     if indent_level:  # Allow imports in conditional statement/function
         return

testsuite/E40.py

@@ -43,6 +43,10 @@
 #: Okay
 if False:
     import foo
+elif not True:
+    import bar
+else:
+    import mwahaha
 
 import bar
 #: E402