Problem:
The frameworks added to apps by macdeployqt cannot be signed by codesign
Symptom:
codesign -s identity --deep --force Foo.app
Foo.app: replacing existing signature
Foo.app: bundle format unrecognized, invalid, or unsuitable
In subcomponent: Foo.app/Contents/Frameworks/QtCore.framework
Solution:
Bah...I can never remember how to do this. Some guy's python script which blah-blah-blah and which didn't work and needs modification blah-blah-blah.
Other solution:
Run macdeployqt as usual. Remove Frameworks/ directory and replace with this version of Frameworks. Then codesign -s identity --deep --force your entire app bundle. This is Qt 4.8.6, as distributed by HomeBrew, with default options.
Trivia:
Apparently still an active bug in Qt5!