Add example of finding latest change to a file.

examples/latest_change.py

@@ -0,0 +1,21 @@
+#!/usr/bin/python
+# Example printing the last author of a specified file
+
+import sys
+import time
+from dulwich.repo import Repo
+
+if len(sys.argv) < 2:
+    print "usage: %s filename" % (sys.argv[0], )
+    sys.exit(1)
+
+r = Repo(".")
+
+w = r.get_walker(paths=[sys.argv[1]], max_entries=1)
+try:
+    c = iter(w).next().commit
+except StopIteration:
+    print "No file %s anywhere in history." % sys.argv[1]
+else:
+    print "%s was last changed at %s by %s (commit %s)" % (
+        sys.argv[1], c.author, time.ctime(c.author_time), c.id)