Labels don't seem to work

[rn]

For some linuxkit tests I tried adding a labels such as:

# LABELS: darwin,linux

with the intention that they would only be run on macOS (darwin) and Linux.

I've added this to all of the linuxkit.kernel tests but when run on macOS:

# rtf list  linuxkit.kernel
STATE           TEST                                    LABELS
[...]
SKIP     linuxkit.kernel.config_4.4.x            darwin, linux
SKIP     linuxkit.kernel.config_4.9.x            darwin, linux
SKIP     linuxkit.kernel.config_4.11.x           darwin, linux
SKIP     linuxkit.kernel.kmod_4.9.x              darwin, linux
[...]

tests are skipped. However:

rtf list -l linux linuxkit.kernel
STATE           TEST                                    LABELS
[...]
RUN      linuxkit.kernel.config_4.4.x            linux, darwin
RUN      linuxkit.kernel.config_4.9.x            darwin, linux
RUN      linuxkit.kernel.config_4.11.x           darwin, linux
RUN      linuxkit.kernel.kmod_4.9.x              linux, darwin
[...]

But:

rtf list -l darwin linuxkit.kernel
STATE           TEST                                    LABELS
[...]
SKIP     linuxkit.kernel.config_4.4.x            linux, darwin
SKIP     linuxkit.kernel.config_4.9.x            darwin, linux
SKIP     linuxkit.kernel.config_4.11.x           darwin, linux
SKIP     linuxkit.kernel.kmod_4.9.x              darwin, linux
[...]

It would also be good if leading or trailing whitespaces would be stripped, so that one can write:

# LABELS: darwin, linux