Strange behaviour of PkgConfigProbe in Product

Product with PkgConfigProbe is not working as expected.
If I create Product with PkgConfigProbe and connect probeId.found with "condition" property of Product, this would happen:
1.) probeId.found == false, so condition is false and Product is disabled by qbs during resolve.
2.) After that PkgConfigProbe reports that library is found and at that moment probeId.found == true
3.) Nevertheless, condition is unaffected, so Product would be disabled during build.

Simple example: https://gist.github.com/nico-izo/1593e0a0d6d938dd2599
I asked one user with the same QBS 1.4.1, but he cannot confirm that strange behaviour (sample_output2.txt)

Latest affected version: qbs 1.4.1 from qtcreator

Version from master branch is unaffected and working as expected.