Offer git commit --amend after previous git commit (#764)

thefuck/rules/git_commit_amend.py

@@ -0,0 +1,11 @@
+from thefuck.specific.git import git_support
+
+
+@git_support
+def match(command):
+    return ('commit' in command.script_parts)
+
+
+@git_support
+def get_new_command(command):
+    return 'git commit --amend'