cubicweb-mercurial-server #3105463 Add check on SSH connection availability before attempting to use hg over SSH [validation pending]

This would make debugging easier.

prioritynormal
typeenhancement
done in0.4.0
load2.000
load left0.000
closed by#2bdecb5ef615 Use mercurial-server SSH API for remote repository creation when applicable
patchBacked out changeset 3c56c228c640 "Implement remote (SSH) and local repository deletion" [applied]Add an entity adapter for Repository to handle SSH connection and operations [applied]Implement remote (SSH) and local repository deletion [applied]Add a check on SSH connection in repository pull_push method [applied]Use mercurial-server SSH API for remote repository creation when applicable [applied]Add a note about SSH keys and agent in README [applied]