Why does shasum generate non-standard hashes?
shasum is working fine but echo "" doesn't produce an empty string:

pse@Fourecks:~$ echo "" | od
0000000    000012                                                         
0000001


This works better:

pse@Fourecks:~$ echo -n "" | shasum
da39a3ee5e6b4b0d3255bfef95601890afd80709