The signals example is overly complex, involving an unneeded go routine and an additional signal. This creates indirection making the code hard to understand.
The proposed change simplifies the code by removing the go routine and the additional signal, leaving the fundamental concept.
This bugfix implements correct way to calculate source sha1 hash, before it will changed,
by propagation of unchanged sources.
This commit will also include regenerated static files and *.hash files.
