Sorting table with `Time` column fails

Trying to sort a table with a time column fails:

from astropy.time import Time
from astropy.table import Table
from astropy.coordinates import EarthLocation
t = Table()
t['a'] = Time([100.0, 200.0], scale='tt', format='mjd',
              location=EarthLocation(-2446354, 4237210, 4077985, unit='m'))
t['b'] = [3, 1]
t.sort('b')

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-60-186ab71ceb04> in <module>()
      6               location=EarthLocation(-2446354, 4237210, 4077985, unit='m'))
      7 t['b'] = [3, 1]
----> 8 t.sort('b')

~/conda-main/envs/ipyfits/lib/python3.6/site-packages/astropy/table/table.py in sort(self, keys)
   2475 
   2476         for col in self.columns.values():
-> 2477             col[:] = col.take(indexes, axis=0)
   2478 
   2479         if sort_index is not None:

TypeError: 'Time' object does not support item assignment

(Apologies if all of the issues I’m opening here are known issues or the expected behavior)

[taldcroft]

Yes sorting relies on Time being mutable which is a new feature of 3.1!

[bsipocz]

@mwcraig - I suspect it’s not, I vaguely remember the sorting is relying on a new feature/API change added after the LTS (but somehow cannot find the PRs now).