My workarounds for this at the moment are to install tools that increase the kernel entropy pool.
If not a virtual machine, and `grep -i -o -m 1 rdrand /proc/cpuinfo` returns 'rdrand', then I install the 'rng-tools5' package which uses the hardware rng in many cpu's to provide entropy to the kernel.
If that fails or if it's a virtual machine, then I install the 'haveged' package.
Note: Neither of these are fixes. They're work-arounds for the current issue that allow somewhat normal operation. eg; Some people have issues around how random the hardware rng is in some machines.
PS: Have seen a number of people suffering this issue in #debian on freenode, and also on #debian & #debian-next on oftc.