cubicweb-mercurial-server #2772906 exec_in_repo: also clone if it was created in the same transaction [validation pending]

some test suites trigger such a call that may fail because the repo is not yet cloned

prioritynormal
typebug
done in0.2.1
load0.200
load left0.000
closed by#e3082752050a [entities] ensure the repo is cloned before working inside (closes #2772906 )
patch[entities] ensure the repo is cloned before working inside (closes #2772906 ) [applied]