patman: Support Series-name tag to name a series

Sometimes it is possible to forget the name of the branch you used to
generate an upstream series. To assist with this, add an optional
patman does not use this.

Signed-off-by: Simon Glass <sjg@chromium.org>

tools/patman/README

@@ -133,6 +133,11 @@ Series-prefix: prefix
 	Sets the subject prefix. Normally empty but it can be RFC for
 	RFC patches, or RESEND if you are being ignored.
 
+Series-name: name
+	Sets the name of the series. You don't need to have a name, and
+	patman does not yet use it, but it is convenient to put the branch
+	name here to help you keep track of multiple upstreaming efforts.
+
 Cover-letter:
 This is the patch set title
 blah blah

tools/patman/series.py

@@ -25,7 +25,7 @@ import gitutil
 import terminal
 
 # Series-xxx tags that we understand
-valid_series = ['to', 'cc', 'version', 'changes', 'prefix', 'notes'];
+valid_series = ['to', 'cc', 'version', 'changes', 'prefix', 'notes', 'name'];
 
 class Series(dict):
     """Holds information about a patch series, including all tags.
@@ -76,7 +76,7 @@ class Series(dict):
             self[name] = value
         else:
             raise ValueError("In %s: line '%s': Unknown 'Series-%s': valid "
-                        "options are %s" % (self.commit.hash, line, name,
+                        "options are %s" % (commit.hash, line, name,
                             ', '.join(valid_series)))
 
     def AddCommit(self, commit):