I think you still don't get this whole "git" thing. Commits are just read-only collections of diff chunks plus metadata, nothing more. It's up to you to define where the boundary is for "bad commits shouldn't be here". Git commits are nothing like SVN or CVS commits (or whatever they're called).
Trying to use some other arcane or error-prone mechanism for getting changes onto test machines is exactly what will leak bad code, because inevitably people will end up sending around zips full of code from who-knows-where for who-knows-which-change.
If you're going to condescend to a stranger, be right. A commit conceptually has a tree of complete blobs that git will diff as needed. git has options that make it more or less sensitive to differences even between unrelated files, so it ignores any delta encoding that may or may not be used in packfiles (and never in loose objects).
If you're making an efficiency argument, git doesn't really try to beat the rsync algorithm even if you ignore the metadata. If you're making a "some people know git and nothing else" argument, fix the team, because that's a serious deficiency.
> A commit conceptually has a tree of complete blobs that git will diff as needed
You're a bit confused about the difference between "concept" and "implementation". There's multiple ways to conceptualize git, but the one I offered is the one presented by the default porcelain while the one you offered is closer to the implementation. The encoding used for storage is entirely irrelevant to my point.
Anyways, my point had nothing to do with efficiency but was related to the topic at hand; that is, whether it it safe to use git to put code on test machines, and indeed whether that's safer than the alternatives. Nothing you said really addresses that point.
Trying to use some other arcane or error-prone mechanism for getting changes onto test machines is exactly what will leak bad code, because inevitably people will end up sending around zips full of code from who-knows-where for who-knows-which-change.