cmds/core/wget: Fix unit test unused port
cmds/core/wget: Fix unit test unused port

The unused port was closed before acquiring the server port.
Thus, the unused port may be the same as server port and fail the test.

Signed-off-by: Medicine Yeh <ce0f0ca58c98e036a28df53229ac3ccdc6eee9c7@gmail.com>

u-root/u-root,u-root/u-root,u-root/u-root