Hi,
On cups version 2.3.0, it has become impossible to modify a printer URI:

# lpadmin -p Test -v file:///dev/null
# lpadmin -p Test -v lpd://192.168.1.2/binary_p1
lpadmin: Unable to open PPD "/tmp/a8f355d839755": Astérisque manquant à la colonne 1 on line 1.

The configuration is a stock configuration, and "/tmp/a8f355d839755" contains some html content that correspond to a kind of garbage you could see in localhost:631/printer/Test.ppd (note the ppd at the end of the url)