!ep->esb_stat is either 1 or 0, and the rightmost bit of ESB_ST_COMPLETE is
always 0, making the result of !ep->esb_stat & ESB_ST_COMPLETE always 0.
Thus parentheses around the argument to ! seem needed.
The semantic patch that makes this change is as follows:
(http://www.emn.fr/x-info/coccinelle/)