Jenkins continually re-triggered by SCM/git

I fixed this once and then promptly forgot what the problem was, so this time I'm writing it down :-)

I use a Unix-based Jenkins master with a Windows-based slave running Microsoft Visual Studio and other stuff that can't be run natively.

I setup my projects so that they use SCM polling and on a couple of occasions I've found that projects just rebuild ad infinitum.

My problem was that I didn't carefully follow the case of the SCM branch specified. Unix is case-sensitive and Windows is case-insensitive; it seems that the Unix part that decides if a new build is required fails-safe (and triggers a build) whereas the Windows part that checks out the source doesn't fail if the wrong case is used.

When I make the SCM Branch Specifier use the correct case everything goes back to normal.