...
back=`pwd`; for d in `find . -type d -name .git`; do cd "$d/.."; pwd; git co develop; cd $back ; done
before hand.
Checking the if branches are out of date:
Another variation on the theme is viewing which of your local branches need pull-ing:
back=`pwd`; for d in `find . -type d -name .git`; do cd "$d/.."; pwd; git remote show origin | grep out\ of\ date; cd $back ; done