update to latest HEAD
    
    - docs: Escape dashes in command-line options
    - chdir("/") if $PWD does not exist. BZ 1001629
    - modifyrepo: automatic option defaults
    - modifyrepo: sanitize opts.sumtype. BZ 1013614
    - modifyrepo: Add <open-size> element. BZ 1013601
    - modifyrepo --remove: fix multiple bugs. BZ 1013626
    - modifyrepo: fix handling of already compressed input. BZ 1013733