localize_tso unnecessary calls?

[jbrockmendel]

Related: #17876, #17734

In tslib._localize_tso there are 4 of blocks of the form:

        if obj.value != NPY_NAT:
            pandas_datetime_to_datetimestruct(obj.value + delta,
                                              PANDAS_FR_ns, &obj.dts)
        else:
            pandas_datetime_to_datetimestruct(obj.value,
                                              PANDAS_FR_ns, &obj.dts)

But in the case where obj.value == NPY_NAT, can't we skip the call to pandas_datetime_to_datetimestruct because we're going to end up with NaT anyway?

[gfyoung]

@jbrockmendel : There's one way to find out: remove the calls and run the tests 😄

[jbrockmendel]

Doesn't cause any test failures; kind of hoping for outside confirmation though.

[jbrockmendel]

This can be fixed in a follow-up after #17875 is closed