[blame] links should show blame for parent of the commit.

[GoogleCodeExporter]

What steps will reproduce the problem?
1. open e.g 
https://chromium.googlesource.com/chromium/src/+blame/ce6f591cf3cd7fe9c4a2cf40ff
a9f70db20d2865/printing/backend/cups_helper.cc
2. click [blame] link on line 1

Result: same blame page.

Expected: blame page for revision just before the commit for line "1"
Particularly here 
https://chromium.googlesource.com/chromium/src/+blame/30b33994dbd7d1e7b28725eab3
cb098dcf8ceca9/printing/backend/cups_helper.cc

Original issue reported on code.google.com by [email protected] on 17 Sep 2014 at 6:43