imerge directly appends to commit messages, ignoring/breaking footers

[talios]

When imerge finishes its rebase-with-history it appends the git commit messages with an information fact about the change, but it appends this blindly against the bottom of the commit message, rather than injecting it above any footers that happen to be present.

In this instance, the footers are being used by the Gerrit code review tool and trigger gerrit into creating duplicate review entries.

Removed collections from AgreementItem

Change-Id: I3587019fabd05348dfcf3f89cd9421f24c3f9c1f

(rebased-with-history from commit 70b69c80d9f5131cdc023d39dd341d11f67d43be)

[talios]

Hrm, on second thoughts - maybe this is actually more desirable, at least in the case of rebased-with-history as the original commit is still linked in the hierarchy, and having Gerrit overrite it would be.... nasty.