[pypy-issue] [issue1355] Difference from CPython when extending a list with an iterable that depends on that list.

[Alex Gaynor]

Alex Gaynor <alex.gaynor at gmail.com> added the comment:

This occurs because CPython does the equivilant of `list` on the argument to `+=`, 
while PyPy merely attempts to iterate over it. It's not obvious to me why 
CPython's behavior is more correct, or more in line with the documentation. With 
that said it's an obvious compatibility difference, perhaps CPython should be 
changed ;)

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nosy: +agaynor
status: unread -> chatting

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