message: Make testing of path independent of absolute paths setup.
  We can not assume that the full absolute path is the same
  for the UpwardFileSearch() as it does realpath(). We only
  know that 'our' part of the filesystem construction will
  match.
diff: @@ -195,17 +195,20 @@ TEST(FileUtil, UpwardFileSearchTest) {
  // Same directory
  EXPECT_OK(file::UpwardFileSearch(file::JoinPath(root_dir, "foo"), "foo-file",
  &result));
  - EXPECT_EQ(result, file::JoinPath(root_dir, "foo/foo-file"));
  + // We don't compare the full path, as the UpwardFileSearch() makes it an
  + // realpath which might not entirely match our root_dir prefix anymore; but
  + // we do know that the suffix should be the same.
  + EXPECT_TRUE(absl::EndsWith(result, "up-search/foo/foo-file"));
  // Somewhere below
  EXPECT_OK(file::UpwardFileSearch(file::JoinPath(root_dir, "foo/bar/baz"),
  "foo-file", &result));
  - EXPECT_EQ(result, file::JoinPath(root_dir, "foo/foo-file"));
  + EXPECT_TRUE(absl::EndsWith(result, "up-search/foo/foo-file"));
  // Find toplevel file
  EXPECT_OK(file::UpwardFileSearch(file::JoinPath(root_dir, "foo/bar/baz"),
  "toplevel-file", &result));
  - EXPECT_EQ(result, file::JoinPath(root_dir, "toplevel-file"));
  + EXPECT_TRUE(absl::EndsWith(result, "up-search/toplevel-file"));
  // Negative test.
  auto status = file::UpwardFileSearch(file::JoinPath(root_dir, "foo/bar/baz"),
  