patman: Make dry-run output match real functionality

When run with the --dry-run argument patman prints out information
showing what it would do.  This information currently doesn't line up
with what patman/git send-email really do.  Some basic examples:
- If an email address is addressed via "Series-cc" and "Patch-cc" patman
  shows that email address would be CC-ed two times.
- If an email address is addressed via "Series-to" and "Patch-cc" patman
  shows that email address would be sent TO and CC-ed.
- If an email address is addressed from a combination of tag aliases,
  get_maintainer.pl output, "Series-cc", "Patch-cc", etc patman shows
  that the email address would be CC-ed multiple times.

Patman currently does try to send duplicate emails like the --dry-run
output shows, but "git send-email" intelligently removes duplicate
addresses so this patch shouldn't change the non-dry-run functionality.

Change patman's output and email addressing to line up with the
"git send-email" logic.  This trims down patman's dry-run output and
prevents confusion about what patman will do when emails are actually
sent.

Signed-off-by: Peter Tyser <ptyser@xes-inc.com>
Acked-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/patman/gitutil.py b/tools/patman/gitutil.py
index cc5a55a..c593070 100644
--- a/tools/patman/gitutil.py
+++ b/tools/patman/gitutil.py
@@ -392,7 +392,8 @@
                    "Or do something like this\n"
                    "git config sendemail.to u-boot@lists.denx.de")
             return
-    cc = BuildEmailList(series.get('cc'), '--cc', alias, raise_on_error)
+    cc = BuildEmailList(list(set(series.get('cc')) - set(series.get('to'))),
+                        '--cc', alias, raise_on_error)
     if self_only:
         to = BuildEmailList([os.getenv('USER')], '--to', alias, raise_on_error)
         cc = []