It seems a bit... inefficient... to re-clone a repository under someone else's control every time you want to update something.
So, why should AUR packages be different from any other form of source code?
It shouldn't be. I just haven't gotten around to setting up a git repo somewhere else to mirror my AUR PKGBUILDs. That being said, at the time of writing the OP, I was scrambling for a local copy before panicking and running off to the mailing list.
Thankfully most of them are cloned now, so this shouldn't be much of a problem.
If you want a good example of a way to manage multiple AUR packages, this is what I do (uses git subtrees): https://github.com/eli-schwartz/pkgbuilds/tree/base
It has the advantage of preventing common maintainer mistakes
(forgetting to update .SRCINFO/updpkgsums, autofilling default commit messages, handling remotes on-the-fly for new packages, etc.)
Basically, additional reasons for being ordered about this sort of thing, in case you weren't convinced already. :)
Oh sweet! I currently just have a dedicated subfolder for my AUR PKGBUILDs, but none of the niceties that this provides. Thanks a bunch!