This change removes a `warnings.simplefilter` call that forced
`DeprecationWarning` occurrences (whether they are generated by this
library or any other code) to be displayed to the user. This call caused
Jenkins Job Builder, for example, to display several developer-targeted
warnings that are not helpful to the final user.
According to the Python documentation:
> Warnings that are only of interest to the developer are ignored by
> default. […] Having certain warnings ignored by default is done to
> prevent a user from seeing warnings that are only of interest to the
> developer. […] While you as a developer want to be notified that your
> code is using a deprecated module, to a user this information is
> essentially noise and provides no benefit to them.
(https://docs.python.org/2/library/warnings.html#updating-code-for-new-versions-of-python)
Change-Id: I31d4c6bd494361aa153fd59e2ceb6bedccd280bc
5cbdccfb81