Squashing your commits into one commit without using interactive rebase (https://github.com/edx/edx-platform/wiki/How-to-Rebase-a-Pull-Request#squash-your-changes)
This basically takes the diff of your branch + origin/master and sets them aside for you to "recommit" them.
git fetch -ap # get in sync w/ server
git checkout jscs-disallow-redundant-spaces # switch to the appropriate branch
git reset --hard origin/jscs-disallow-redundant-spaces # get my branch to be exactly the same as what's on the server
MERGE_BASE=$(git merge-base origin/jscs-disallow-redundant-spaces origin/master) # get the commit where your branch originates
git reset --mixed $MERGE_BASE # reset to the point where your branch originates, but put your changes like you just made them