qbs config --global fails silently if permissions are insufficient (Linux)

If run by a normal unprivileged user, any command which attempts to write to the global qbs preferences will fail silently, returning 0 and with no error message, but without writing the preference.

This includes shortcut commands such as “qbs setup-qt /usr/bin/qmake system-qt” as well as normal ones such as “qbs config --global platform gcc”.

If the command is run as a priviliged user (e.g. by prefixing with “sudo ”), the configuration is correctly saved.

Qbs should tell the user (and return a non-zero return code) if it is unable to write a preference.