Add git rpr command

Signed-off-by: Emile Vauge <emile@vauge.com>

.github/rpr.sh

@@ -0,0 +1,35 @@
+#!/bin/sh
+#
+# git config --global alias.rpr '!sh .github/rpr.sh'
+
+set -e # stop on error
+
+usage="$(basename "$0") pr -- rebase a Pull Request against current branch"
+
+if [ "$#" -ne 1 ]; then
+    echo "Illegal number of parameters"
+    echo "$usage" >&2
+    exit 1
+fi
+
+command -v jq >/dev/null 2>&1 || { echo "I require jq but it's not installed.  Aborting." >&2; exit 1; }
+
+set -x # echo on
+
+base=$(git rev-parse --abbrev-ref HEAD)
+pr=$1
+remote=$(curl -s https://api.github.com/repos/containous/traefik/pulls/$pr | jq -r .head.repo.owner.login)
+branch=$(curl -s https://api.github.com/repos/containous/traefik/pulls/$pr | jq -r .head.ref)
+
+git checkout $base
+
+git remote add $remote git@github.com:$remote/traefik.git
+git fetch $remote $branch
+git checkout -t $remote/$branch
+git rebase origin/$base
+git push -f $remote $branch
+
+# clean
+git checkout $base
+git branch -D $branch
+git remote remove $remote