Add a don't repeat yourself rule

thefuck/rules/dry.py

@@ -0,0 +1,12 @@
+def match(command, settings):
+    split_command = command.script.split()
+
+    return len(split_command) >= 2 and split_command[0] == split_command[1]
+
+
+def get_new_command(command, settings):
+    return command.script[command.script.find(' '):]
+
+# it should be rare enough to actually have to type twice the same word, so
+# this rule can have a higher priority to come before things like "cd cd foo"
+priority = 900