[9fans] test(1) support for string length (-l) in p9p?

[dexen deVries]

the man page of test(1) mentions "-l string" as string length operator
for -eq, -gt, etc.
but there seems to be nothing in the plan9port's src/cmd/test.c, nor
in 9p.io/sources/cmd/test.c

is there any implementation of this floating around?