both off 
event queue:
	0	a : 1
	0	b : 0
time: 0
pull with strong first 
event queue:
	10	c : 0	[from b:=1]
weak pull should lose fight 
expect instability to be suppressed 
event queue:
	10	c : 0	[from b:=1]
time: 10
de-assert weak 
time: 10
de-assert strong 
time: 10
