removed redundant code and fixed an invalid read of size 1 in ...unpadfour()

tests/unittests.cfg

@@ -347,7 +347,7 @@ temporarily disabled
 <test check-if-catch-missing-newlines>
   prepare = perl -e 'print "X" x 5000; print "\n"' > testfile-toolong
   cmd = $pcp -V $vault -P -I testfile-toolong
-  expect = /line is too long/
+  expect = /Error: decoded input/
 </test>
 
 /*