CIFS_MOUNT: Mount fails if server is specified with FQDN

Specifying a FQDN for the SERVER parameter seems to make the mount fail. For example:

SERVER="SERVERNAME"
SHARE="SHARENAME"
USERNAME="USERNAME"
PASSWORD="PASSWORD"
LOCAL_DIR="_Arcade/MAME|_Arcade/HBMAME|ScummVM/Games|Games|bootrom|NeoGeo|_TAS|ao486"
MOUNT_AT_BOOT="true"
WAIT_FOR_SERVER="true"
ADDITIONAL_MOUNT_OPTIONS="vers=2.1"

The above settings in my INI work.

SERVER="SERVERNAME.domain.com"
SHARE="SHARENAME"
USERNAME="USERNAME"
PASSWORD="PASSWORD"
LOCAL_DIR="_Arcade/MAME|_Arcade/HBMAME|ScummVM/Games|Games|bootrom|NeoGeo|_TAS|ao486"
MOUNT_AT_BOOT="true"
WAIT_FOR_SERVER="true"
ADDITIONAL_MOUNT_OPTIONS="vers=2.1"

This change to the SERVER option, however, returns:

Waiting for SERVERNAME.domain.com
mount: /tmp/cifs_mount: bad option; for several filesystems (e.g. nfs, cifs) you might need a /sbin/mount. helper program.
//The/MiSTer not mounted
Done!

And nothing gets mounted.

I've verified that the FQDN is correct, as I can ping it from my MiSTer just fine, so something seems to be up with how the script parses that string. I also see the same results even if I take out the ADDITIONAL_MOUNT_OPTIONS, and reduce LOCAL_DIR to just "Games", so neither of those seems to be related.

Start at the CIFS_MOUNT script entry point and reproduce the supplied SERVER values, comparing the short hostname with the FQDN. Done means the same configuration mounts the share successfully with the FQDN while preserving the existing short-hostname behavior.