Additional source files that start with RCS are no longer included in a project

[tobiasisenberg]

Bug Report

Current behavior

MyOwnTest.zip
If you try to compile the attached example that includes external local files, this fails. This used to work in 1.8.9. The effect started in 1.8.10. This only happens for specific included file names, namely *.h and *.cpp files that start with "RCS".

Interestingly, if the name of *.ino file is "test" or "bug" I get a completely different compile error:
panic: runtime error: invalid memory address or nil pointer dereference
Very strange, you can try it out by renaming *.ino and directory to bug.

Expected behavior

The code compiles normally.

Environment

• CLI version (output of arduino-cli version): 1.8.10
• OS and platform: Windows 10, 64bit

Additional context

[matthijskooijman]

I suspect this changed due to #366

[masci]

The function used in #366 is supposed to filter out files within folders called RCS so this is a bug, a source tree like the attached archive must compile without problems.