I changed my github username. This sh helped find all my local workspace repos and fix the remote url (and https auth, if necessary)

updaterepos-find.sh

#!/usr/bin/env bash

# MIT License: *especially* the warranty\liability limitations.
# Please be responsible when using bash to recursively alter git repos.
#
# usage ./updaterepos-find.sh

# where to start find.
base="/home/me/workspaces"
# github username mapping
olduser=oldusername_here
newuser=newusername_here
# auth mapping - if you use https remotes (https://user:[email protected]/user/repo/repo.git) and need to normalize the pass part.
oldauth=oldauthstring_here
newauth=newauthstring_here

for local in `find ${base} -maxdepth 5 -type d -iname ".git"`; do
    cd "${local}/.."
    echo "[x] In: $(pwd)"
    remote=$(git remote -v)
    echo "${remote}"

    if [ "${remote}" = "" ]; then
       echo "[-]no remote"
    else
        IFS='    ' read -r -a repoparts <<< ${remote}
        reponame=${repoparts[0]}
        repourl=${repoparts[1]}

        if [[ ${repourl} == *"${newuser}"* ]]; then
            echo "checking repo parts..."
            printf "    %s\n" "${repoparts[@]}"
            echo ""

            #-- rewrite
            newurl=$(sed -e "s|${olduser}|${newuser}|g" <<< ${repourl})
            newurl=$(sed -e "s|${oldauth}|${newauth}|g" <<< ${newurl})
            cmd="git remote set-url ${reponame} ${newurl}"

            #-- execute
            printf "[-]Preparing to:\n${cmd}\n"
             eval ${cmd}
        else
            echo 'not your repo'
        fi

        echo "[O]Done"
    fi
    echo "===================="
done

And of course there's a bug :)
if [[ ${repourl} == *"${newuser}"* ]]; then should be if [[ ${repourl} == *"${olduser}"* ]]; then