The Debian autobuilders encountered a heisenbug building my last upload of fossil to Debian, 2011.01.01.030647-1.  Although I'm not sure, because I could not reliably replicate the problem even on an 8-way machine with -j8, I suspect it is because the include file targets in src/main.mk are, e.g., "add.h" rather than "$(OBJDIR)/add.h".  Which I changed with the obvious patch,


and uploaded in 2011.01.01.030647-2.  Will soon see if this fixes the build issue: