Revert "Merge pull request #7001 from shoyer/NaT-comparison"

This reverts commit 7141f40b58ed1e7071cde78ab7bc8ab37e9c5983,
reversing changes made to 8fa6e3bef26a6d4a2c92f2824129aa4409be2590.

The original broke some pandas tests. The current plan to get this
in is

* reversion
* issue FutureWarning in 1.11 and 1.12
* make the change in 1.13.

1 files changed, 3 insertions, 3 deletions

diff --git a/numpy/core/arrayprint.py b/numpy/core/arrayprint.py
index c5b5b5a8f..fefcb6493 100644
--- a/numpy/core/arrayprint.py
+++ b/numpy/core/arrayprint.py
@@ -739,8 +739,8 @@ class DatetimeFormat(object):
 class TimedeltaFormat(object):
     def __init__(self, data):
         if data.dtype.kind == 'm':
-            # select non-NaT elements
-            v = data[data == data].view('i8')
+            nat_value = array(['NaT'], dtype=data.dtype)[0]
+            v = data[not_equal(data, nat_value)].view('i8')
             if len(v) > 0:
                 # Max str length of non-NaT elements
                 max_str_len = max(len(str(maximum.reduce(v))),
@@ -754,7 +754,7 @@ class TimedeltaFormat(object):
             self._nat = "'NaT'".rjust(max_str_len)
 
     def __call__(self, x):
-        if x != x:
+        if x + 1 == x:
             return self._nat
         else:
             return self.format % x.astype('i8')