changing this doc string

[andrewkern]

editing the warning introduced in #1955 for clarity as to what the issue is

[codecov]

Codecov Report

Merging #1962 (7d2baa2) into main (30678bb) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #1962   +/-   ##
=======================================
  Coverage   91.17%   91.17%           
=======================================
  Files          20       20           
  Lines       10677    10677           
  Branches     2209     2209           
=======================================
  Hits         9735     9735           
  Misses        516      516           
  Partials      426      426           

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C	91.17% <ø> (ø)
python	98.75% <ø> (ø)

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Impacted Files	Coverage Δ
msprime/ancestry.py	99.10% <ø> (ø)

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[petrelharp]

I'm confused - what does it mean if you run it back to a high initial frequency, if not a "sweep from standing genetic variation"?

[andrewkern]

that you aren't conditioning on allele frequency dynamics back in time, past when the allele hit the final frequency

[molpopgen]

I'm confused - what does it mean if you run it back to a high initial frequency, if not a "sweep from standing genetic variation"?

It means that you've taken a structured coalescent back to some point determined by "initial frequency" and then suddenly unstructure it (b/c there's no merged API that means "finish it w/a neutral trajectory").

[jeromekelleher]

LGTM