[7u8] Request for approval from 7167593/7167976/7170091: Changed get_source.sh to allow for getting full oracle jdk repo forest

[Seán Coffey]

I'd like to backport Kelly's changes to jdk7u repo. I plan on preserving 
the changesets to keep the
code consistent across 8 & 7u.

7167976 & 7170091 are simple follow up bug records to fix/tweak the 
script further.

7167593 : http://hg.openjdk.java.net/jdk8/build/rev/955a3e8ed4f0
7167976 : http://hg.openjdk.java.net/jdk8/build/rev/8a4e92c10a9a
7170091 : http://hg.openjdk.java.net/jdk8/jdk8/rev/dd596160b323

regards,
Sean.