ENH: Timestamp pickle support non-nano tzaware (#47340)

Author: jbrockmendel

pandas/_libs/tslibs/timestamps.pyx

@@ -157,14 +157,7 @@ cdef inline _Timestamp create_timestamp_from_ts(
 
 def _unpickle_timestamp(value, freq, tz, reso=NPY_FR_ns):
     # GH#41949 dont warn on unpickle if we have a freq
-    if reso == NPY_FR_ns:
-        ts = Timestamp(value, tz=tz)
-    else:
-        if tz is not None:
-            raise NotImplementedError
-        abbrev = npy_unit_to_abbrev(reso)
-        dt64 = np.datetime64(value, abbrev)
-        ts = Timestamp._from_dt64(dt64)
+    ts = Timestamp._from_value_and_reso(value, reso, tz)
     ts._set_freq(freq)
     return ts
 

pandas/tests/scalar/timestamp/test_timestamp.py

@@ -22,6 +22,7 @@
 from pandas._libs.tslibs.timezones import (
     dateutil_gettz as gettz,
     get_timezone,
+    maybe_get_tz,
     tz_compare,
 )
 from pandas.errors import OutOfBoundsDatetime
@@ -836,7 +837,10 @@ def test_cmp_cross_reso_reversed_dt64(self):
 
         assert other.asm8 < ts
 
-    def test_pickle(self, ts):
+    def test_pickle(self, ts, tz_aware_fixture):
+        tz = tz_aware_fixture
+        tz = maybe_get_tz(tz)
+        ts = Timestamp._from_value_and_reso(ts.value, ts._reso, tz)
         rt = tm.round_trip_pickle(ts)
         assert rt._reso == ts._reso
         assert rt == ts