System Information
Operating system: Linux-4.15.0-50-generic-x86_64-with-debian-buster-sid 64 Bits
Graphics card: GeForce GTX 1080 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 410.104

Blender Version
Broken: version: 2.80 (sub 74), branch: master, commit date: 2019-06-20 22:36, hash: rB197661c7334d

Short description of error
A hair particle system on an object without a material will momentarily disappear when a new material is added to the object. Triggering an update by changing the number of hairs causes the hair to reappear.

Exact steps for others to reproduce the error (adding material)

1. delete the default cube as it already has a material
2. add a cube (which doesn't have any material yet)
3. add a particle system to the cube and change it to hair
4. add a material to the cube
5. observe that the hair disappeared when it shouldn't have
6. change the number of hairs to make the hair reappear

Exact steps for others to reproduce the error (removing material)

1. add a particle system to the default cube and change it to hair
2. remove the default cube's material
3. observe that the hair disappeared when it shouldn't have
4. change the number of hairs to make the hair reappear

Other ways that I found for producing the error
-Toggling the "show emitter" option (for particles)
-Changing the particle system name