Default arguments not respected (and query broken?) when "Share arguments" is NOT indicated

Related to the fix at #644174: Share arguments won't work

The where clause I'm trying to create is this one...

WHERE (node.type in ('school')) AND (node.status = 1) AND (term_node.tid = 719 OR term_node.tid = 777)

The number 719 needs to be passed in via an argument and the number 777 needs to be fixed.

For the second term ID, I chose to add a second argument (that I know will never be provided) and set the "Action to take if argument is not present" to "Provide default argument" with a "Fixed entry" of 777.

When I check the box for "Share arguments" on the "Views Or: Next alternative" argument everything works as expected, and the query generated is

WHERE ((node.type in ('school')) AND (node.status = 1)) AND (((term_node.tid = 719) AND (term_node.vid IS NOT NULL)) OR (term_node2.tid = 719))

You can see that it is comparing both term_node.tid and term_node2.tid to 719 (the argument)

However, when I UNcheck the box for "Share arguments" on the "Views Or: Next alternative" argument the query refuses to run at all:

No query was run

Un-doing the patch provided at #644174: Share arguments won't work solved my issue. :/ Reverting to the previous if / else statement generates the correct where clause

WHERE ((node.type in ('school')) AND (node.status = 1)) AND (((term_node.tid = 719) AND (term_node.vid IS NOT NULL)) OR (term_node2.tid = 777))