Made the actual max value clearer

src/Products/PluginIndexes/DateIndex/DateIndex.py

@@ -51,7 +51,8 @@ else:
     DSTOFFSET = STDOFFSET
 
 DSTDIFF = DSTOFFSET - STDOFFSET
-MAX32 = 2**31
+MAX32 = 2**31 - 1
+
 
 class LocalTimezone(tzinfo):
 
@@ -264,9 +265,7 @@ class DateIndex(UnIndex, PropertyManager):
 
         t_val = ( ( ( ( yr * 12 + mo ) * 31 + dy ) * 24 + hr ) * 60 + mn )
 
-        
-
-        if t_val >= MAX32:
+        if t_val > MAX32:
             # t_val must be integer fitting in the 32bit range
             raise OverflowError(
                 "%s is not within the range of indexable dates (index: %s)"

src/Products/PluginIndexes/DateRangeIndex/DateRangeIndex.py

@@ -37,7 +37,7 @@ from Products.PluginIndexes.common.util import parseIndexRequest
 from Products.PluginIndexes.interfaces import IDateRangeIndex
 
 _dtmldir = os.path.join( package_home( globals() ), 'dtml' )
-MAX32 = 2**31
+MAX32 = 2**31 - 1
 
 
 class DateRangeIndex(UnIndex):
@@ -398,7 +398,7 @@ class DateRangeIndex(UnIndex):
         elif isinstance(value, DateTime):
             value = value.millis() / 1000 / 60 # flatten to minutes
         result = int( value )
-        if result >= MAX32:
+        if result > MAX32:
             # t_val must be integer fitting in the 32bit range
             raise OverflowError( '%s is not within the range of dates allowed'
                               'by a DateRangeIndex' % value)