Change in behaviour of Series from 11.1

Question

In 11.0,

Series[(1 - Sqrt[1-4z])/2, {z, 1/4, 1}]

gives

1/2 - I Sqrt[z-1/4] + O[z-1/4]^(3/2)

as one would expect. From 11.1 (and still in 11.3), the output is

(1/2 - 1/2 Sqrt[1-4z]) + O[z-1/4]^2

Even worse,

SeriesCoefficient[(1 - Sqrt[1-4z])/2, {z, 1/4, 0}]

now returns 1/2 - 1/2 Sqrt[1-4z] which is nonsense, rather than the correct answer of 1/2. Similarly,

SeriesCoefficient[(1 - Sqrt[1-4z])/2, {z, 1/4, 1/2}]

now gives 0 rather than -I.

This is presumably related to this, but is not yet fixed and seems like a more fundamental failure in the handling of Puiseux series to me.

This has broken a lot of code I regularly use.