Old .Po file references old directory, how to start fresh?

[Travis Pressler]

Hi,

I'm learning how to make an autotools project and have created a test project 
to work with. I ran make with a directory `nested` and then deleted it and 
deleted the reference to it in my `Makefile.am`.

Now I'm running ./configure && make​ and I get the following:

*** No rule to make target 'nested/main.c', needed by 'main.o'. Stop.​

How can I run `make` so that it doesn't reference this old nested​ directory?

I was curious if I could find where this reference is, so I did a grep -r 
nested .​ I think the only relevant hit is:

./src/.deps/main.Po:main.o nested/main.c /usr/include/stdc-predef.h 
/usr/include/stdio.h \​

Many Thanks
-Travis