Bug#958531: pandas: broken by NaT/isnan changes in numpy 1.18

[Rebecca N. Palmer]

Package: python3-pandas
Version: 0.25.3+dfsg-9
Severity: serious
Tags: fixed-upstream patch

numpy 1.18 includes two behaviour changes that affect pandas, causing a 
CI fail / presumed FTBFS.

Both are fixed in pandas 1.0 (in experimental, but moving that to 
unstable causes other issues, see #950430).

- NaT sorts to the end rather than the beginning

This causes an actual behaviour change for Index (but not values) 
sorting, not just broken tests.

Fix: 
https://github.com/pandas-dev/pandas/commit/f85502531806df4f3c0233edffe9460f3ee26031#diff-26a6d2ca7adfca586aabbb1c9dd8bf36

- np.isinf/isnan no longer raise on datetime/timedelta data type

Breaks tests that assert they raise.

Fix: 
https://github.com/pandas-dev/pandas/commit/0c0adfbc291fc1b1e9afad592f5275e783ffd0b0#diff-af2644300e4b344f0c048fe3adde10e0