The crash happens due to wrong 'digits' variable value(0),
'digits' can not be 0, so the fix is use 1 as min allowed value.


mysql-test/r/insert.result:
  test result
mysql-test/t/insert.test:
  test case
sql/field.cc:
  The crash happens due to wrong 'digits' variable value(0),
  'digits' can not be 0, so the fix is use 1 as min allowed value.