solving the error when running gem install or gem update

when seeing
ERROR: While executing gem ... (ArgumentError)
    uri scheme is invalid

try looking into your gem sources
run
gem sources

and then remove all weird or unnecessary sources
until you are left with only http://gems.rubyforge.org

then try to install or update a gem and you'll hopefully not see this
bug

i removed
http://gems.rubyonrails.org
http://gems.github.com/

which one of them caused the problem