Regression with Qbs 1.6 and Bullseye Coverage

We’re using a tool called Bullseye Coverage for measuring code coverage with Visual Studio compilers on Windows. When the Bullseye "integration" for Visual Studio compilers is enabled, the installer adds one line to the end of each of the vcvarsXX.bat files in <vc-install-dir>/VC/bin:

@set PATH=c:/BullseyeCoverage/bin;%PATH%

The Bullseye bin folder contains a specific version of the compiler shell (cl.exe) which does some source code preprocessing in case Bullseye instrumentation is active at the moment. In any case the original compiler shell from the next occurrence in PATH is called to do the actual work.

This approach is working fine with Qbs, but since Qbs 1.6 (as contained in QtCreator 4.1 beta) we observe a major regression. With Bullseye integration on (which means the PATH modification in the .bat files is active), Qbs refuses to load the project and reports:

<...>\MsvcProbe.qbs:47: error: Error: Detecting the MSVC build environment failed: Cannot find 'C:\BullseyeCoverage\vcvarsall.bat'.

Note that this tool combination (Bullseye, Visual Studio 20xx, Qbs) has been working well for about a year until QtCreator 4.0.2.