A function in a Blueprint Function Library that references another function in that library cannot be saved after closing and reopening the project

A function in a Blueprint Function Library that references another function in that library cannot be saved after closing and reopening the project. The library will save without error until the project is closed. Removing the reference allows the library to be saved again.

Reproduced in 4.7.1 binary and Main (//depot/UE4/Promotable-CL-2455917)

1. Open any project
2. Create a new Blueprint Function Library
3. Name the default function, "Foo"
4. Add a second function, "Bar"
5. Make Foo call Bar
6. Compile/Save/Close editor
7. Reopen the project
8. Save the function library

Result:
"Can't save D:/4.7_Projects/BPFuncLibSave/Content/NewFunctionLibrary.uasset: Graph is linked to private object(s) in an external package.
External Object(s):
/Engine/Transient

Try to find the chain of references to that object (may take some time)?"

The function library cannot be saved unless Bar is deleted from the Foo graph.