sympy/sympy — pull request #2177 by Upabjojr (2013-06-15 14:30:22+00:00)
Title: fixing args in tensor module

Added these tests and fixed an issue in `TensorHead`'s `args`.

```
assert type(a)(*a.args) == a
assert type(Lorentz)(*Lorentz.args) == Lorentz
assert type(p)(*p.args) == p
assert type(p(a))(*(p(a)).args) == p(a)
assert type(t1)(*t1.args) == t1
assert type(t3)(*t3.args) == t3

assert hash(type(a)(*a.args)) == hash(a)
assert hash(type(Lorentz)(*Lorentz.args)) == hash(Lorentz)
assert hash(type(p)(*p.args)) == hash(p)
assert hash(type(p(a))(*(p(a)).args)) == hash(p(a))
assert hash(type(t1)(*t1.args)) == hash(t1)
assert hash(type(t3)(*t3.args)) == hash(t3)
```