SolusIO update fails to download installer

Symptoms 

SolusIO update fails with the error:

SVM_ERROR: Failed to download Update
failed to update installer binary to new version "1.1.18616" from url "http://installer.dev.solusvm.com/testing/1.1.18616/installer"

Cause

SolusIO bug #SIO-3337 that had been fixed in Version 1.1.19227

Resolution

Update SolusIO manually.