By the way, I found the following error message in the build log: make[3]: Entering directory `/var/obj/pkg.150001/www/firefox/work/mozilla/security/coreconf' syntax error at -e line 3, near "while" syntax error at -e line 7, near "}" Execution of -e aborted due to compilation errors.
This appears like syntax errors in a perl script given on the command line (perl -e 'bluh bluh'), but the build proceeds anyway.
