rails/rails — pull request #12702 by dmathieu (2013-10-30 14:06:38+00:00)
Title: session#fetch doesn't behave exactly like Hash#fetch.

Mention it in the changelog and add a test checking for regressions.

Hash#fetch isn't adding the defaultly returned value.
However, in the session, saving it is the behavior we should expect.

See discussion in #12692