the TaskBrowser did not assist to its math's courses ; )

Here is the taskBrowser output in 1.10 :

In Task AgvDeployer[R]. (Status of last Command : none )
(type 'ls' for context info) :1 - 1 + 1
Got :1 - 1 + 1
= -1

It priorises the second 1+1 operation that makes 2, and then do the
substraction 1 - 2 instead of 1 - 1 and then +1