[duplicate-code] Remove trailing whitespaces in similarity report

And fix tests/checkers/unittest_similar.py that required to have some

ChangeLog

@@ -22,6 +22,9 @@ Release date: TBA
 
   Closes #4648
 
+* The ``similarity`` checker no longer add three trailing whitespaces for
+  empty lines in its report.
+
 
 What's New in Pylint 2.9.2?
 ===========================

pylint/checkers/similar.py

@@ -127,7 +127,7 @@ def _get_similarity_report(self, similarities: List[Tuple]) -> str:
                 report += f"=={line_set.name}:{idx}\n"
             if line_set:
                 for line in line_set._real_lines[idx : idx + number]:
-                    report += f"   {line.rstrip()}\n"
+                    report += f"   {line.rstrip()}\n" if line.rstrip() else "\n"
             duplicated_line_number += number * (len(files) - 1)
         total_line_number: int = sum(len(lineset) for lineset in self.linesets)
         report += "TOTAL lines={} duplicates={} percent={:.2f}\n".format(

tests/checkers/unittest_similar.py

@@ -175,7 +175,7 @@ def test_ignore_signatures_fail():
        arg5: int = 5
    ) -> Ret1:
        pass
-   
+
    def example():
        """Valid function definition with docstring only."""
 TOTAL lines=29 duplicates=10 percent=34.48