--icmp-ipid does not affect the identifier in ICMP echo requests

Command-line argument --icmp-ipid updates variable icmp_ip_id which is never used to set the identifier field in the ICMP header of echo requests (icmp type 8). Instead, in sendicmp.c getpid() is used to set variable icmp->un.echo.id which I'm guessing is the default behavior (random identifier).