Add git-lfs download/extract script

.gitignore

@@ -2,3 +2,4 @@
 *.jugdata/
 /.tmp/
 /logs/
+/bin/git-lfs-linux-amd64-v*/

scripts/download_extract_git-lfs.sh

@@ -0,0 +1,49 @@
+#!/bin/bash
+source scripts/utils.sh echo -n
+
+# Saner programming env: these switches turn some bugs into errors
+set -o errexit -o pipefail
+
+# this script is meant to be used with 'datalad run'
+
+# Download git-lfs
+_VERSION=v2.13.3
+
+mkdir -p bin/git-lfs-linux-amd64-${_VERSION}
+rm -f bin/sha256sums
+echo "03197488f7be54cfc7b693f0ed6c75ac155f5aaa835508c64d68ec8f308b04c1  git-lfs-linux-amd64-${_VERSION}.tar.gz" > bin/sha256sums
+
+files_url=(
+	"https://github.com/git-lfs/git-lfs/releases/download/${_VERSION}/git-lfs-linux-amd64-${_VERSION}.tar.gz bin/git-lfs-linux-amd64-${_VERSION}.tar.gz")
+
+git-annex addurl --fast -c annex.largefiles=anything --raw --batch --with-files <<EOF
+$(for file_url in "${files_url[@]}" ; do echo "${file_url}" ; done)
+EOF
+# Downloads should complete correctly but in multiprocesses the last git-annex
+# step most likely fails on a BGFS with the error "rename: resource busy
+# (Device or resource busy)"
+! git-annex get --fast -J8
+# Remove the last byte from each files to prevent the "download failed:
+# ResponseBodyTooShort" error
+ls -l $(list) | grep -oE "\.git/[^']*" | \
+	cut -d'/' -f7 | xargs -n1 -- find .git/annex/tmp/ -name | \
+	while read f
+	do
+		newfsize=$(($(stat -c '%s' "${f}") - 1))
+		chmod +w "${f}"
+		truncate -s $newfsize "${f}"
+	done
+# Retry incomplete downloads
+git-annex get --fast --incomplete
+git-annex migrate --fast -c annex.largefiles=anything *
+(cd bin/
+ sha256sum -c sha256sums) || \
+exit_on_error_code "Failed to download git-lfs"
+
+# Install git-lfs
+tar -C bin/git-lfs-linux-amd64-${_VERSION} -xf bin/git-lfs-linux-amd64-${_VERSION}.tar.gz || \
+exit_on_error_code "Failed to extract git-lfs"
+
+pushd bin/ >/dev/null
+ln -sf git-lfs-linux-amd64-${_VERSION}/git-lfs .
+popd >/dev/null