The culprit is line 34:
sequence c_files = dir(builddir)
Executed without a trailing slash, $(BUILDDIR)\intobj returns just that $(BUILDDIR)\intobj, not the items inside of $(BUILDDIR)\intobj. This was fixed in RC2 by adding a trailing slash to the makefile target but needs fixed properly going forward.
Also, while editing coverage.ex, make it abort(1) on errors.
Fixed problems in be_machine.c w/string handling. dir("intobj") previously would realize intobj was a directory and append "
*" to the end. The append was not being handled correctly.