Force overwriting the file if it already exists.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@6080 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/utils/NightlyTest.pl b/utils/NightlyTest.pl
index 39dca2c..b8b6f4c 100755
--- a/utils/NightlyTest.pl
+++ b/utils/NightlyTest.pl
@@ -292,7 +292,7 @@
   }
 
   # Compress the test output
-  system "gzip $Prefix-ProgramTest.txt";
+  system "gzip -f $Prefix-ProgramTest.txt";
 }
 
 my ($TestsAdded, $TestsRemoved, $TestsFixed, $TestsBroken) = ("","","","");