[ixpmanager] v5.8.0 upgrade question . . .

[Paul Emmons]

Ok something I haven't run into before. I getting stuck on step 3 
(https://docs.ixpmanager.org/install/upgrading/) :

root at portal:/srv/ixpmanager# git fetch --all
Fetching origin
remote: Enumerating objects: 308, done.
remote: Counting objects: 100% (273/273), done.
remote: Compressing objects: 100% (96/96), done.
remote: Total 308 (delta 203), reused 242 (delta 177), pack-reused 35
Receiving objects: 100% (308/308), 768.08 KiB | 3.80 MiB/s, done.
Resolving deltas: 100% (208/208), completed with 86 local objects.
 From https://github.com/inex/IXP-Manager
    9c727d55a..19dd74cc7  release-v5 -> origin/release-v5
    fe1bba432..19dd74cc7  master     -> origin/master
  * [new branch]          sage       -> origin/sage
root at portal:/srv/ixpmanager# git checkout v5.8.0
error: pathspec 'v5.8.0' did not match any file(s) known to git