fetchdarcs: add {pre,post}Fetch hooks (#469215)

runHook preFetch

tagtext=""

tagflags=""

# Darcs hashes are sha1 (120 bits, 40-character hex)

# Repository list may contain ?. No glob expansion for that.

set -o noglob

success=

for repository in $repositories; do

    echo "Trying to clone $repository $tagtext into $out …"

    if darcs clone --lazy $tagflags "$repository" "$out"; then

        # remove metadata, because it can change

        rm -rf "$out/_darcs"

        exit 0

        success=1

        break

    fi

done

set +o noglob

if [ -z "$success" ]; then

    echo "Error: couldn’t clone repository from any mirror" 1>&2

    exit 1

fi

runHook postFetch