fix bug 9221. When calculating the project root, don't use sourcepaths that don't exist
source.. = src/
output.. = bin/
bin.includes = plugin.xml,\
META-INF/,\
.,\
html/,\
index/,\
icons/,\
book.css
src.includes = META-INF/,\
html/,\
icons/,\
plugin.xml,\
book.css