This patch addresses the issue raised in T88340.
When entering a pose sliding operator bones would automatically get hidden.
While technically not a bug it was decided that it is too confusing.
Hiding with 'H' is still possible though, just won't happen automatically
Reviewed by: Sybren A. Stüvel
Differential Revision: https://developer.blender.org/D11883
Ref: D11883
aa32121174