makes gitweb URL points to full sha1

makes gitweb URL points to full sha1

The URL we are crafting are using a short sha1 (7 chars long) which can
have some good chance of pointing to two different sha1. I have seen git
log to use 8 chars from time to time because of sha1 collisions, 62
occurences outu of 45315 commits as of now.

So to play it safe, this patch makes the URL points to the full sha1.

Follow https://gerrit.wikimedia.org/r/4335
5734eac351dcd72f493bfd7547a5f638f582b048 (commit)
9afc1eff1c396a4d0273d2226e316cba2fb44ab0 (merge)

Change-Id: Ic65d0ca89916fe43999b9e3f257d9f322198f9f8