Are the attributes in a Python class shared or not?

The following code troubles me:-

class mytest:
    name="test1"
    tricks=list()
    def __init__(self,name):
        self.name=name
        #self.tricks=[name]
        self.tricks.append(name)

t1=mytest("hello world")
t2=mytest("bye world")
print t1.name,t2.name
print t1.tricks,t2.tricks

The output is:-

hello world bye world
['hello world', 'bye world'] ['hello world', 'bye world']

meaning that the list tricks is shared by the two instances t1 and t2, which has been explained in the section 9.3.5 of https://docs.python.org/3/tutorial/classes.html

However, if I execute the following code:-

class mytest:
    name="test1"
    tricks=list()
    def __init__(self,name):
        self.name=name
        self.tricks=[name]
        self.tricks.append(name)

t1=mytest("hello world")
t2=mytest("bye world")
x=t1.tricks
if type(x) is list:
    print 'a list'
elif type(x) is tuple:
    print 'a tuple'
else:
    print 'neither a tuple or a list'
print t1.name,t2.name
print t1.tricks,t2.tricks

The output is the following:-

a list
hello world bye world
['hello world', 'hello world'] ['bye world', 'bye world']

Now it seems that the list tricks is no longer shared by those two instances t1 and t2. My question is, what are the mechanics here?