Operating system: Darwin-18.5.0-x86_64-i386-64bit 64 Bits
Graphics card: Intel(R) Iris(TM) Graphics 6100 Intel Inc. 4.1 INTEL-12.8.38
Broken: version: 2.81 (sub 9), branch: master, commit date: 2019-09-09 17:22, hash: rB6be3348505ce
It doesn't work on 2.8 as well
Short description of error
When using "Use for Growing Hair" in "Field Weights" I'd expect that selected forces will be used for modelling hair, but the total hair length will be the same as specified in "Hair Length" field. Instead forces affect hair length as well.
Using forces for modelling hair would be very useful (e.g. to simulate collision with head and avoid buggy Dynamic Hair that requires animation steps) but currently is not very usable because of this issue.
Could Blender make constraint when using forces for growing hair so each grown segment is of equal length? (i.e. make forces affect direction of hair, not their length).