Added a PyPy incompatibility workaround.

httpie/compat.py

@@ -4,7 +4,10 @@ Python 2.6, 2.7, and 3.x compatibility.
 """
 # Borrow these from requests:
 # noinspection PyUnresolvedReferences
-from requests.compat import is_windows, bytes, str, is_py3, is_py26, is_pypy
+from requests.compat import (
+    is_windows, bytes, str,
+    is_py3, is_py26, is_pypy, is_py27
+)
 
 try:  # pragma: no cover
     # noinspection PyUnresolvedReferences,PyCompatibility

httpie/input.py

@@ -8,7 +8,7 @@ import errno
 import mimetypes
 import getpass
 from io import BytesIO
-from collections import namedtuple
+from collections import namedtuple, Iterable
 # noinspection PyCompatibility
 from argparse import ArgumentParser, ArgumentTypeError, ArgumentError
 
@@ -16,7 +16,7 @@ from argparse import ArgumentParser, ArgumentTypeError, ArgumentError
 # https://github.com/jakubroztocil/httpie/issues/130
 from requests.structures import CaseInsensitiveDict
 
-from httpie.compat import OrderedDict, urlsplit, str
+from httpie.compat import OrderedDict, urlsplit, str, is_pypy, is_py27
 from httpie.sessions import VALID_SESSION_NAME_PATTERN
 from httpie.utils import load_json_preserve_order
 
@@ -561,6 +561,17 @@ class AuthCredentialsArgType(KeyValueArgType):
 class RequestItemsDict(OrderedDict):
     """Multi-value dict for URL parameters and form data."""
 
+    if is_pypy and is_py27:
+        # Manually set keys when initialized with an iterable as PyPy
+        # doesn't call __setitem__ in such case (pypy3 does).
+        def __init__(self, *args, **kwargs):
+            if len(args) == 1 and isinstance(args[0], Iterable):
+                super(RequestItemsDict, self).__init__(**kwargs)
+                for k, v in args[0]:
+                    self[k] = v
+            else:
+                super(RequestItemsDict, self).__init__(*args, **kwargs)
+
     #noinspection PyMethodOverriding
     def __setitem__(self, key, value):
         """ If `key` is assigned more than once, `self[key]` holds a