Adding note to updating about time_compare

UPDATING.md

@@ -44,6 +44,11 @@ creation of permissions set `FAB_UPDATE_PERMS = False` on config.
 which adds missing non-nullable fields and uniqueness constraints to the metrics
 and sql_metrics tables. Depending on the integrity of the data, manual
 intervention may be required.
+* [7616](https://github.com/apache/incubator-superset/pull/7616): this bug fix
+changes time_compare deltas to correctly evaluate to the number of days prior
+instead of number of days in the future. It will change the data for advanced
+analytics time_compare so `1 year` from 5/1/2019 will be calculated as 365 days
+instead of 366 days.
 
 ## Superset 0.32.0
 

superset/utils/core.py

@@ -315,8 +315,11 @@ def parse_human_timedelta(s: str) -> timedelta:
 def parse_past_timedelta(delta_str: str) -> timedelta:
     """
     Takes a delta like '1 year' and finds the timedelta for that period in
-    the past. parse_human_timedelta('-1 year') returns datetime.timedelta(-365), so
-    we need to return -datetime.timedelta(-365) or datetime.timedelta(365).
+    the past, then represents that past timedelta in positive terms.
+
+    parse_human_timedelta('1 year') find the timedelta 1 year in the future.
+    parse_past_timedelta('1 year') returns -datetime.timedelta(-365)
+    or datetime.timedelta(365).
     """
     return -parse_human_timedelta(
         delta_str if delta_str.startswith('-') else f'-{delta_str}')