mergetool: check return value from read

diff --git a/RelNotes b/RelNotes
index a433be58b7bdd4a7004f9762e1f44c4aafecd1b3..5fcc4ef74770e8587a1469fff5e3f5610dabf0e1 120000 (symlink)
--- a/RelNotes
+++ b/RelNotes
@@ -1 +1 @@
-Documentation/RelNotes-1.6.3.2.txt
\ No newline at end of file
+Documentation/RelNotes/1.7.6.txt
\ No newline at end of file