Mis-detection of namespaces

We occasionally "need" patches like https://codereview.qt-project.org/c/qt-creator/qt-creator/+/644938 to convince lupdate to put messages in the right context.

This patch is currently in Creator 17.0 branch. Reverting the patch and running 'ninja ts_de' yields the attached diff, where lupdate effectively "forgets" about the QtC::Debugger context and "invents" an unrelated "Tr" context.

This only happens for a few translations, and we haven't found an obvious pattern so far.