This solves several problems that arise from the special treatment of "=" in Bash. The fix was required as some log drivers have options in a key=value form. It also addresses the --option=value and the negated boolean syntax (--boolean=false). Note that this is not a general fix for these problems, it is limited to the __docker_pos_first_nonflag function. Signed-off-by: Harald Albers <github@albersweb.de>