Searches on multi select fields giving incorrect results

1) Searches for one of several options of a multi select can produce invalid results.
To reproduce:

• create a custom field for individuals of type alphanumeric multi-select with options: 'one' -> 1, 'two -> 2, 'ten' -> 10
• create user1 with 'ten'
• in advanced search, set the custom field to search for 'one', 'two' and 'any'
• the results wrongly include user1 with 'ten'

2) As above, but in Reports

• with the same setup, go to Constituent Summary report, filter for 'one'
• report wrongly includes user1

3) Searches for 'all' with a multi select fail

• with the same custom fields as above
• set the field to 'one', 'two' on user1 and 'one' on user2
• in advanced search, set the custom field to search for 'one', 'two' and 'all'
• the results wrongly show both users