0.28.1 (2018-03-18)

Bugs fixed

• PyFrozenSet_New() was accidentally used in PyPy where it is missingfrom the C-API.
• Assignment between some C++ templated types were incorrectly rejectedwhen the templates mix const with ctypedef.(Github issue #2148)
• Undeclared C++ no-args constructors in subclasses could make the compilationfail if the base class constructor was declared without nogil.(Github issue #2157)
• Bytes %-formatting inferred basestring (bytes or unicode) as result typein some cases where bytes would have been safe to infer.(Github issue #2153)
• None was accidentally disallowed as typed return value of dict.pop().(Github issue #2152)