Why escape char `:' with `\' when auto completing filenames?

[Clark J. Wang]

For example:

# touch ifcfg-eth-id-00:0c:29:b5:71:d2
# ls ifcfg<TAB>

After pressing the <TAB> the command line will become to:

# ls ifcfg-eth-id-00\:0c\:29\:b5\:71\:d2

That's a bit annoying. I think char `:' is not special in bash. Any
reasonable consideration for the behavior?

-- 
Clark