Add rule to remove a doubled-up "git clone" in a git clone command. (#1106)

Some git hosts will copy the entire clone command, while others just
copy the url, so typing "git clone ", then pasting a git url that
already has a "git clone " on the front is a somewhat common issue.

tests/rules/test_git_clone_git_clone.py

@@ -0,0 +1,24 @@
+from thefuck.rules.git_clone_git_clone import match, get_new_command
+from thefuck.types import Command
+
+
+output_clean = """
+fatal: Too many arguments.
+
+usage: git clone [<options>] [--] <repo> [<dir>]
+"""
+
+
+def test_match():
+    assert match(Command('git clone git clone foo', output_clean))
+
+
+def test_not_match():
+    assert not match(Command('', ''))
+    assert not match(Command('git branch', ''))
+    assert not match(Command('git clone foo', ''))
+    assert not match(Command('git clone foo bar baz', output_clean))
+
+
+def test_get_new_command():
+    assert get_new_command(Command('git clone git clone foo', output_clean)) == 'git clone foo'