Is replacing a value during iteration of a mapping safe in Python?

Neil G :

Is code like this guaranteed to work in Python?

d = {k: 2 * k for k in range(10)}

for k, v in d.items():
    d[k] = v + 1

As far as I know, deleting a key doesn't work, and neither does adding a key?

I know that I can work around this problem by rebuilding the dict (by using a comprehension, for example).

Edit: I'm looking for a reference showing this to be guaranteed to work in Python (not, for example, that it happens to work in the current implementation of CPython).

Heap Overflow :

The documentation warns about adding and deleting:

Iterating views while adding or deleting entries in the dictionary may raise a RuntimeError or fail to iterate over all entries.

If changing the value for an existing key were also dangerous, I'm sure they'd mention that as well.