updated for version 7.4.052
Problem:    With 'fo' set to "a2" inserting a space in the first column may
	    cause the cursor to jump to the previous line.
Solution:   Handle the case when there is no comment leader properly. (Tor
	    Perkins)  Also fix that cursor is in the wrong place when spaces
	    get replaced with a Tab.
Added tag v7-4-052 for changeset b9c1c1f4cda9