[kogeler]

xpra printing-info never exits when there is no system D-Bus, which is common
in containers: it prints the printer list and then hangs until interrupted.
init_printing() falls back to the CUPS polling timer, a non-daemon thread which
re-arms itself every 60 seconds. For the same reason, the printing-info check in
unit.scripts.main_test fails after its 60 second timeout on such hosts.

The command only takes a snapshot or submits a job and never uses printer change
notifications, so don't initialize them there. The client still initializes and
cleans up its own watcher.

The new test runs printing-info with an unreachable system bus and CUPS server:
it times out without this change and exits with the connection error with it.

[totaam]

This module was also used on win32 as Print.exe:

xpra/setup.py

Lines 2896 to 2897 in 4b839ed

	if printing_ENABLED:
	add_console_exe("xpra/platform/printing.py", "printer.ico", "Print")

But I believe it has now been superseded by PDFIUM_Print.exe:

xpra/setup.py

Lines 2849 to 2851 in 4b839ed

	if printing_ENABLED:
	add_console_exe("xpra/platform/win32/pdfium.py", "printer.ico", "PDFIUM_Print")
	do_add_DLLs("", "pdfium")

As used here:

xpra/xpra/platform/win32/printing.py

Line 218 in 4b839ed

command = ["PDFIUM_Print.exe", filename, printer, title]

So I'm going to merge this despite having some doubts. Thanks!