i18n: proposed command missing leading dash
i18n: proposed command missing leading dash

Add missing leading dash to proposed commands in french output when
using the command:
    git branch --set-upstream remotename/branchname
and when upstream is gone

Signed-off-by: Sandy Carter <d5b81245cbf34ee99706e14204dadf8c7126c8d8@savoirfairelinux.com>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git