Add author.py

This script prints out the commit author from `git log` output.  Used
to update AUTHORS file.

author.py

@@ -0,0 +1,52 @@
+#!/usr/bin/env python
+
+# script to extract commit author's name from standard input.  The
+# input should be <AUTHOR>:<EMAIL>, one per line.
+# This script expects the input is created by git-log command:
+#
+#   git log --format=%aN:%aE
+#
+# This script removes duplicates based on email address, breaking a
+# tie with longer author name.  Among the all author names extract the
+# previous step, we remove duplicate by case-insensitive match.
+#
+# So we can do this in one line:
+#
+#   git log --format=%aN:%aE | sort | uniq | ./author.py > authors
+
+import sys
+
+edict = {}
+
+for line in sys.stdin:
+    author, email = line.strip().split(':', 1)
+    if email in edict:
+        an = edict[email]
+        if len(an) < len(author) or an > author:
+            sys.stderr.write(
+                'eliminated {} in favor of {}\n'.format(an, author))
+            edict[email] = author
+        else:
+            sys.stderr.write(
+                'eliminated {} in favor of {}\n'.format(author, an))
+    else:
+        edict[email] = author
+
+names = list(sorted(edict.values()))
+
+ndict = {}
+
+for name in names:
+    lowname = name.lower()
+    if lowname in ndict:
+        an = ndict[lowname]
+        if an > name:
+            sys.stderr.write('eliminated {} in favor of {}\n'.format(an, name))
+            ndict[lowname] = name
+        else:
+            sys.stderr.write('eliminated {} in favor of {}\n'.format(name, an))
+    else:
+        ndict[lowname] = name
+
+for name in sorted(ndict.values()):
+    print name