Utils: Fix FilePath::withTildeHomePath()

Or rather, re-instate previous behavior.

Amends c9023e85108.

Change-Id: I1be0dd8c42db8430323b8368a8164b1623d5ced5
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

src/libs/utils/filepath.cpp

@@ -1705,8 +1705,9 @@ QString FilePath::withTildeHomePath() const
 
     QString outPath = cleanPath().absoluteFilePath().path();
     if (outPath.startsWith(homePath))
-        outPath = '~' + outPath.mid(homePath.size());
-    return outPath;
+       return '~' + outPath.mid(homePath.size());
+
+    return toString();
 }
 
 QTextStream &operator<<(QTextStream &s, const FilePath &fn)