Handle two repos with the same relative_url in the single content set.
    
    Without this commit, when there are two repos in single content set
    sharing the same relative_url, ODCS tries to create and lock single
    file lock twice, because the locks are based on the relative_url. This
    leads to deadlock.
    
    It also calls mergerepo_c with the same repo twice which is waste
    of resources.
    
    This commit changes it, so we remove duplicated repos before calling
    mergerepo_c.
    
    It also adds 1800 seconds timeout to mergerepo_c to ensure it does not
    block whole process forever in case of issues.