Add 'rebase="false"' attribute to the <project/> XML.

This new attribute can prevent 'repo sync' from automatically rebasing.

I hit a situation in where one of the git repositories I was tracking
was actually an external repository that I wanted to pull commits
into and merge myself. (NOT rebase, since that would lose the merge
history.) In this case, I'm not using 'repo upload', I'm manually
managing the merges to and from this repository.

Everything was going great until I typed 'repo sync' and it rebased
my manually-merged tree. Hence the option to skip it.

Change-Id: I965e0dd1acb87f4a56752ebedc7e2de1c502dbf8
2 files changed