dd conv=unblock: print final newline consistently

* src/dd.c (dd_copy) [C_UNBLOCK]: Always print the final newline for
non-empty output, not just when output size is a multiple of cbs.
* doc/coreutils.texi (dd invocation) [conv=unblock]: Mention that dd
prints a newline after each output record, not just when replacing
trailing spaces.
Reported by Ulrich Drepper.
* tests/dd/unblock: New file.  Test for this.
* tests/Makefile.am (TESTS): Add it.
* NEWS (Bug fixes): Mention it.

1 files changed, 5 insertions, 4 deletions

diff --git a/src/dd.c b/src/dd.c
index 04665f98f..76a31e981 100644
--- a/src/dd.c
+++ b/src/dd.c
@@ -1785,10 +1785,11 @@ dd_copy (void)
         output_char (space_character);
     }
 
-  if ((conversions_mask & C_UNBLOCK) && col == conversion_blocksize)
-    /* Add a final '\n' if there are exactly `conversion_blocksize'
-       characters in the final record. */
-    output_char (newline_character);
+  if (col && (conversions_mask & C_UNBLOCK))
+    {
+      /* If there was any output, add a final '\n'.  */
+      output_char (newline_character);
+    }
 
   /* Write out the last block. */
   if (oc != 0)