The LineSorter QMTest preprocessor is broken

LineSorter is currently stripping the line contents instead of sorting. In particular, it strips the trailing \n and because it comes after normalizeEOL in the normalizeExamples preprocessor, there are lines without a trailing '\n'. This in turn is a problem for the ReferenceFileValidator where difflib.ndiff does not ignore \n.

The fix is simple:

diff --git GaudiPolicy/python/GaudiTesting/BaseTest.py GaudiPolicy/python/GaudiTesting/BaseTest.py
index 272f9ed79..0ecdab63f 100644
--- GaudiPolicy/python/GaudiTesting/BaseTest.py
+++ GaudiPolicy/python/GaudiTesting/BaseTest.py
@@ -903,10 +903,9 @@ class LineSorter(FilePreprocessor):
     def __processLine__(self, line):
         pos = line.find(self.signature)
         if pos >= 0:
-            line = line[:(pos + self.siglen)]
             lst = line[(pos + self.siglen):].split()
             lst.sort()
-            line += " ".join(lst)
+            line = line[:(pos + self.siglen)] + " ".join(lst)
         return line