Use realpath during relpath to avoid cross-volume issues on Windows. Fixes #436.

Author: jaraco

src/setuptools_scm/file_finder.py

@@ -50,6 +50,6 @@ def _link_not_in_scm(n):
             # dirpath + filename with symlinks preserved
             fullfilename = os.path.join(dirpath, filename)
             if os.path.normcase(os.path.realpath(fullfilename)) in scm_files:
-                res.append(os.path.join(path, os.path.relpath(fullfilename, path)))
+                res.append(os.path.join(path, os.path.relpath(fullfilename, realpath)))
         seen.add(realdirpath)
     return res