Reported by Florian Pelz:
https://lists.gnu.org/archive/html/guix-devel/2020-11/msg00326.html.
* gnu/installer/utils.scm (call-with-time): New procedure,
(let/time): new macro.
* gnu/installer/parted.scm (with-delay-device-in-use?): Increase the retry
count to 16.
(non-install-devices): Remove the call to with-delay-device-in-use? as it
doesn't return the expected result, and would block much longer now.
(free-parted): Log the time required to sync each device.
3d3ffb30f9