Master and maint-3.6 are building non-matching libraries in gitian-utils for Windows
While preparing TBB 3.6.3 it turned out that the libraries built during gitian-utils for Windows are different depending on whether master or maint-3.6 is used. Thus, one can't build from the maint-3.6 and master branch on the same machine without rebuilding all the things the gitian-utils descriptor builds even if the library versions do not change.