Misleading error message when package is not compatible

From this error message it would seem that there is no 9.9.0-rc.6 version:

λ tap package install SDK --version 9.9.0-rc.6
Could not download one or more packages.
Package 'SDK' matching version '9.9.0-rc.6' could not be found. Latest compatible version is '9.9.0-rc.7+acbfac56'.

This also seem so indicate the same:

λ tap package list SDK
9.9.0-rc.7+acbfac56    - AnyCPU - Windows,Linux -
9.9.0-rc.1+8ba28cb1    - AnyCPU - Windows,Linux -
...

However that is just because rc.2 through rc.6 are not compatible (--all argument also lists incompatible versions):

λ tap package list SDK --all
9.9.0-rc.7+acbfac56    - AnyCPU - Windows,Linux -
9.9.0-rc.6+dbb22003    - AnyCPU - Windows,Linux -
9.9.0-rc.5+e17ce5c6    - AnyCPU - Windows,Linux -
9.9.0-rc.4+b8971e31    - AnyCPU - Windows,Linux -
9.9.0-rc.3+97790d20    - AnyCPU - Windows,Linux -
9.9.0-rc.2+a22317f9    - AnyCPU - Windows,Linux -
9.9.0-rc.1+8ba28cb1    - AnyCPU - Windows,Linux -
...

So actually, rc.6 does exist, even though the error message says "version '9.9.0-rc.6' could not be found".