Improve git export with automatic creation and update of authors and branches file.

mirror_to_github.sh

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     rm git-marks1.txt git-marks2.txt
 fi
 touch git-marks1.txt git-marks2.txt
+[ -f git-authors.txt ] || echo '[e-mail] = Lapo Luchini <[e-mail]>' > git-authors.txt
+mtn ls branches --ignore-suspend-certs | sort -V | awk -F . '{ print $0 " = " ($4 ? $4 : "trunk") }' > git-branches.txt
 mtn --quiet --authors=git-authors.txt --branches-file=git-branches.txt --import-marks=git-marks1.txt --export-marks=git-marks1.txt git_export | \
     git fast-import --import-marks=git-marks2.txt --export-marks=git-marks2.txt
 git push --mirror origin