It breaks in the following command
cat file1.dep file2.dep > file3.dep
Furthermore in the future it may break programmers code working with dep files if the programmer assumes (legitimately) that files are following the standard unix text formatting.
Following .dep files are not terminated with 0x0a:
Image-ExifTool.tcz.dep
ImageMagick-dev.tcz.dep
ImageMagick.tcz.dep
Terminal-locale.tcz.dep
Terminal.tcz.dep
Thunar-locale.tcz.dep
amsn-voice-alsa.tcz.dep
balsa-locale.tcz.dep
bitcoin-locale.tcz.dep
bitcoin.tcz.dep
blobwars-locale.tcz.dep
blobwars.tcz.dep
bonnie++.tcz.dep
cinepaint.tcz.dep
circuslinux.tcz.dep
cln-dev.tcz.dep
cln.tcz.dep
dbench.tcz.dep
dbus-c++-dev.tcz.dep
dbus-c++.tcz.dep
dcraw.tcz.dep
djvulibre-dev.tcz.dep
drizzle-client.tcz.dep
drizzle-server-dev.tcz.dep
drizzle.tcz.dep
echinus.tcz.dep
exo-dev.tcz.dep
exo-locale.tcz.dep
exo.tcz.dep
fastjar.tcz.dep
foobillardplus.tcz.dep
glib-networking.tcz.dep
gnuplot.tcz.dep
gsettings-desktop-schemas.tcz.dep
gtk-xfce-engine.tcz.dep
icon-naming-utils.tcz.dep
isomaster-locale.tcz.dep
isomaster.tcz.dep
kdemultimedia.tcz.dep
kdenetwork.tcz.dep
keepassx.tcz.dep
libbsd-dev.tcz.dep
libdrizzle-dev.tcz.dep
libdrizzle.tcz.dep
libdvdnav-dev.tcz.dep
libdvdnav.tcz.dep
libedit-dev.tcz.dep
libedit.tcz.dep
libesmtp-dev.tcz.dep
libesmtp.tcz.dep
libexempi-dev.tcz.dep
libexempi.tcz.dep
libmicrohttpd.tcz.dep
libmpeg2-dev.tcz.dep
libmusicbrainz3-dev.tcz.dep
libmusicbrainz3.tcz.dep
libmxml-dev.tcz.dep
libsee.tcz.dep
libsoup.tcz.dep
libspectre-dev.tcz.dep
libwnck-dev.tcz.dep
libwnck-locale.tcz.dep
libwnck.tcz.dep
libxfce4util-dev.tcz.dep
libxfce4util-locale.tcz.dep
libxfce4util.tcz.dep
libxfcegui4-dev.tcz.dep
libxfcegui4-locale.tcz.dep
libxfcegui4.tcz.dep
libzip-dev.tcz.dep
lxtask.tcz.dep
mame.tcz.dep
mednafen.tcz.dep
mjpegtools.tcz.dep
modernforex.tcz.dep
mpeg2dec.tcz.dep
msmtp.tcz.dep
multiget-locale.tcz.dep
multiget.tcz.dep
nload.tcz.dep
opera-11.tcz.dep
opera-next.tcz.dep
p7zip-full.tcz.dep
pcmanfm-mod-locale.tcz.dep
pcmanfm-mod.tcz.dep
pygoocanvas-2.7.tcz.dep
python-httplib2-2.7.tcz.dep
qtweb.tcz.dep
rarian-dev.tcz.dep
rarian.tcz.dep
rawstudio.tcz.dep
recode-locale.tcz.dep
rtmpdump.tcz.dep
rumus2.tcz.dep
secure_erase.tcz.dep
see-shell.tcz.dep
soundmodem-dev.tcz.dep
soundmodem-locale.tcz.dep
soundmodem.tcz.dep
soundmodemconfig.tcz.dep
squeeze-dev.tcz.dep
squeeze-locale.tcz.dep
tome2.tcz.dep
vcdimager.tcz.dep
webkit-sharp.tcz.dep
xfce4-appfinder-locale.tcz.dep
xfce4-appfinder.tcz.dep
xfce4-goodies-panel-plugins-locale.tcz.dep
yougrabber.tcz.dep
If any application is sensitive for buggy input which can break it, application must handle it as you can not be 100% sure you get proper data input, see above.
Using command line commands you are referring it is up to you to check input.