power series with zero p-adic coefficients

[chriswuthrich]

The following _repr_ does not look good to me

sage: R.<T> = Qp(5,5)[[]]
sage: O(5^3)*T
0
sage: 1+O(5^3)*T
1 + O(5^5) + O(5^3)*T

But that is due to

sage: s= O(5^3)*T
sage: s.is_zero()
True
sage: s == R(0)
False

This I consider to be a bug according to the docstring of s.is_zero? saying

Return True if self equals self.parent()(0).

Component: padics

Keywords: padic powerseries padicIMA

Stopgaps: todo

Issue created by migration from https://trac.sagemath.org/ticket/4656

[roed314]

Attachment: 4656.patch.gz

[chriswuthrich]

Description changed:

--- 
+++ 
@@ -1,4 +1,3 @@
-
 The following `_repr_` does not look good to me
 
 ```

[chriswuthrich]

comment:3

Looks good to me and passes all tests. I changed the patch as the orinigally posted patch does not apply against sage 3.4. Thanks!