AssertionError in LimitValuation

[swewers]

Steps To Reproduce

The following Sage commands produce an error:

v_2 = QQ.valuation(2)
R.<x> = QQ[]
f = x^8 - 7/2*x^6 + 7/2*x^5 - 7/11*x^4 + 7*x^3 + 7/2*x^2 + 49*x + 14
v0 = GaussValuation(R, v_2)
v1 = v0.augmentation(x, 1)
v = LimitValuation(v1, f)
v
v(x)

v is correctly created as a limit valuation:
[ Gauss valuation induced by 2-adic valuation, v(x) = 1 , … ]

but then the computation of the value v(x) causes an error:
AssertionError: a MacLane step produced no augmentation

Expected Behavior

In this situation, the limit valuation is well defined, and the result should be v(x)=1.

Actual Behavior

However, the computation of v(x) causes an assertion error.

Additional Information

The error occurs when the function mac_lane_step of the current approximation of the limit valuation v is called. The assertion statement is

assert not allow_equivalent_key, "a MacLane step produced no augmentation"

Environment

• OS: Ubuntu 20.04
• Sage Version: 10.04

Checklist

• I have searched the existing issues for a bug report that matches the one I want to file, without success.
• I have read the documentation and troubleshoot guide

[swewers]

@saraedum
This should be easy to fix. Why is the assert necessary?