The doc said positive values for a negative range were intermediate
but the code actually rejects them if the value has an overt plus
sign, so make clear that intermediate is only for the case without a
sign. Incidentally comment on a test where it might not have been
obvious to the reader that a space is the locale's digit-grouping
chracter.
Pick-to: 6.5 6.5.0
Change-Id: I3edab74fe8c2cbe8448c0e523676f1fd0d0d8a9f
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
58f5ec35f1