Add git_branch_delete rule
diff --git a/tests/rules/test_git_branch_delete.py b/tests/rules/test_git_branch_delete.py
new file mode 100644
index 000000000..44a8f4490
--- /dev/null
+++ b/tests/rules/test_git_branch_delete.py
@@ -0,0 +1,22 @@
+import pytest
+from thefuck.rules.git_branch_delete import match, get_new_command
+from tests.utils import Command
+
+
+@pytest.fixture
+def stderr():
+    return '''error: The branch 'branch' is not fully merged.
+If you are sure you want to delete it, run 'git branch -D branch'.
+
+'''
+
+
+def test_match(stderr):
+    assert match(Command('git branch -d branch', stderr=stderr), None)
+    assert not match(Command('git branch -d branch'), None)
+    assert not match(Command('ls', stderr=stderr), None)
+
+
+def test_get_new_command(stderr):
+    assert get_new_command(Command('git branch -d branch', stderr=stderr), None)\
+        == "git branch -D branch"
diff --git a/thefuck/rules/git_branch_delete.py b/thefuck/rules/git_branch_delete.py
new file mode 100644
index 000000000..ad465af6a
--- /dev/null
+++ b/thefuck/rules/git_branch_delete.py
@@ -0,0 +1,7 @@
+def match(command, settings):
+    return ('git branch -d' in command.script
+            and 'If you are sure you want to delete it' in command.stderr)
+
+
+def get_new_command(command, settings):
+    return command.script.replace('-d', '-D')

I have never written python before, so this is just copy-pasting and slashing. So if I missed some convention, or wrote the test in some wrong way, please tell me :smile: 

This is to be able to give a fuck in this situation:

![image](https://cloud.githubusercontent.com/assets/1404810/8765750/9baecbfe-2e1c-11e5-85d0-779099328e40.png)
