+ Note that the current submodule support is minimal and this is
+ deliberately so. A design decision we made is that operations
+ at the supermodule level do not recurse into submodules by
+ default. The expectation is that later we would add a
+ mechanism to tell git which submodules the user is interested
+ in, and this information might be used to determine the
+ recursive behaviour of certain commands (e.g. "git checkout"
+ and "git diff"), but currently we haven't agreed on what that
+ mechanism should look like. Therefore, if you use submodules,
+ you would probably need "git submodule update" on the
+ submodules you care about after running a "git checkout" at
+ the supermodule level.
+