Slackware :: Apple Time Capsule DHCP Sets Bogus Hostname?

During Slackware 13.1 setup, I chose the hostname stella-sl2. This hostname is also the one that the system is displaying before I configured network access. After configuring wired network access to my Apple Time Capsule, my hostname suddenly changed to INTERFACE='eth0'. As a result I'm noticing some very strange things, like the login prompt which has become "INTERFACE='eth0' login: ".

After configuring wireless network access to the Time Capsule, the hostname changed to "INTERFACE='wlan0'". Note that, during boot, wlan0 is brought up AFTER eth0.

Also strange is this:

bash-4.1$ cat /etc/HOSTNAME
INTERFACE='eth0'.DNSSERVERS='10.0.1.1'
bash-4.1$ /bin/hostname
INTERFACE='wlan0'
bash-4.1$

Until now, it was only a minor annoyance, it didn't prevent anything from happening, internet connection was not affected. But now I'm configuring sendmail which needs to talk to a relay SMTP server, and sendmail "HELO"'s itself using the bogus hostname:

>>> HELO INTERFACE='wlan0'
<<< 501 HELO requires valid address
554 5.0.0 Service unavailable

Probably this is caused by the Time Capsule not adhering to standards. However, the Time Capsule's firmware is the latest version, so I cannot fix this. Is there a way to prevent dhcp from changing the hostname? How can I make sure that the hostname that I configured during setup remains active?