New submission from Matthew Brett:
The behavior of dict iteration has changed in Python 3.6, in that inserting
keys during iteration has a different and unpredictable affect. For this code:
d = {'foo': 1}
for key in d:
print(key)
d.pop(key)
d[key] = 1
Python 3.5 prints a single 'foo' (one pass through the loop). Python 3.6
generates five lines of 'foo' (five passes through the loop). Of course this
code is pathological, but I found this behavior from a bug in code where the
pathology was a lot less obvious - see https://github.com/nipy/nipy/issues/420
----------
messages: 286794
nosy: matthew.brett
priority: normal
severity: normal
status: open
title: Python 3.6 change in dict iteration when inserting keys
type: behavior
versions: Python 3.6
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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue29420>
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