core-tools .funcignore does not ignore sub-directories when it should

[madelinegordon]

There are multiple issues with the current implementation of the .funcignore parser:

• When for example test2 is included in the .funcignore file, it should ignore /test2 and abc/test2
  (this is also the case for when /test2 is included in the .funcignore file.)

• When test/ is included in the .funcignore file, the directory a/test should be ignored.

These are determined as issues in accordance with current .gitignore patterns.

[kf6kjg]

See #2701 for details. It turns out that there's a deep seated problem with the interpretation of the .funcignore file.