*Possible* fix for #2318.  Not sure if this will fix @cdeil's specific issue, but it *did* fix the issue for me running on my laptop on the institute network.
Allow mask to be set to anything that can be converted to a numpy bool array
Allow flags to be set with array-like in addition to array or FlagCollection
Convert mask and flags input to ndarray
Changelog entry
Use np.intp_t for indices
Adding support for sign (and space) separated sexagesimal coordinates in SkyCoord
Check for and prevent initialization of NDData with Quantity

Closes #2374, though admittedly in an unsatisfactory way.
Add changelog entry
Fix masking in arithmetic

Closes #2403
Add changelog entry
Adding test
Minor rewrite of space separation support
correct numerous errors in documentation
Install wcs headers when using bundled wcslib only
Fix docstrings in modeling. Add a note in wcs docstrings about origin of outputs coordinates
Update changelog for #2536
Install config file.
Make coeff keyword arguments so that a polynomial with default parameters zeroes can be initialized.
fix typo