CreationDate in PDF files' metadata

Greetings,

I document my software using DocBook5 in a Debian GNU/Linux box. When the PDF
files are generated, the CreationDate field gets filled-up using a new value at
each run. This is a problem in our Debian effort to have "reproducible builds"
[0] with the "forensic science" idea that the same code should produce the same
binaries bit-by-bit [1].