The plot thickens. While my build succeeds, I did find an error in the build log when libqcadscripts should have been built, and in light of that your patch makes sense. I applied it (and PLIST) and qcad still builds and runs. I don't understand why upstream doesn't have a library build failure as fatal (it is ignored), and I don't understand why it was fatal for you. I have commited the patch; thanks for reporting.
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