Bug#484288: libx11-dev: Still depends on libxext-dev instead of x11proto-xext-dev
I see from debian/changelog that you already tried to fix the dependency on
libxext-dev in version 2:1.0.0-4. However, it appears that at that time, you
only fixed the Build-Depends on libxext-dev and not the binary Depends of
libx11-dev. As a result, libxext still doesn't bootstrap without manual
intervention, or having libxext-dev already available.