From bug report: http://forum.piwik.org/index.php?showtopic=70
In the config file we should have
username = “my=username”
username = my=username
the same way the password is currently enclosed in double quotes
from #570, host should also be enclosed in quotes.
fixed in 949
—> all non-array values in Config/config.ini.php are now automatically enclosed in double quotes, and double quote automatically encoded as " (parse_ini_file doesn’t handle escaping the double quote, arg)