How to reproduce:

cargo new hello
cd hello
vi Cargo.toml

Add the following line to the package table:

include = ["hello.txt"]

And then create that file:

touch hello.txt

Finally, try to execute

cargo package

This fails for me with the following error message:

   Packaging hello v0.1.0 (file:///home/thomas/Workspace/hello)
   Verifying hello v0.1.0 (file:///home/thomas/Workspace/hello)
error: failed to verify package tarball

Caused by:
  failed to read `/home/thomas/Workspace/hello/target/package/hello-0.1.0/Cargo.toml`

Caused by:
  No such file or directory (os error 2)

Executing ls target/package/hello-0.1.0/ gives me hello.txt, so it does get included.

Tested versions (same result):

• cargo 0.23.0-nightly (e447ac7 2017-09-27)
• cargo 0.22.0 (3423351 2017-10-06)