Ranting about tortoisesvn and it committing new files with CR/LF in them, I finally found that there is apparently no way to make svn behave the right way (in our sense) of doing svn:eol-style=native automatically. You need to do a setup like this. Yet another misdesign. (And if you work on two projects where these defaults differ, then you are out of luck.)
By the way, somehow nobody did think that a by-line diff of svn:externals would be a good thing. We usually have one directory with six or so externals, and when you change one of them svn diff just shows the whole property text as changed, and not individual lines. Tortoisesvn is smarter here (as in other places), reinforcing my claim that with svn you need GUI support because the command line interface isn't exactly pretty.