cubicweb-vcsfile #1958218 don't log traceback on url error or unauthorized when cloning/updatig an hg repo [resolved]

this clutters the log for no benefit

prioritynormal
typebug
done in1.8.7
load0.100
load left0.000
closed by#0df9b4b40201 closes #1958218: don't log traceback on bad url/access denied