IMO Format string field in page admin/config/regional/date-time/formats/add need to be required field. Attached patch will do the needful.
No patch attached
#2: date_format_empty_string_1.patch queued for re-testing.
This patch works as promised.
Committed to CVS HEAD. Thanks.
Automatically closed -- issue fixed for 2 weeks with no activity.
Restoring issue tags, see #2125755: System messages removed all issue tags during D7 upgrade.
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