fix(solvers): handle factorisation better in solveset

[oscarbenjamin]

References to other Issues or PRs

Fixes #23318

Brief description of what is fixed or changed

Properly handle all factors of a factorisable equation in solveset. Previously the equation was factored but the separate factors were not subsequently solved.

Other comments

Release Notes

• solvers
  • A bug preventing solveset from properly handling equations that can be factored was fixed.

[sympy-bot]

✅

Hi, I am the SymPy bot (v167). I'm here to help you write a release notes entry. Please read the guide on how to write release notes.

Your release notes are in good order.

Here is what the release notes will look like:

• solvers
  • A bug preventing solveset from properly handling equations that can be factored was fixed. (#23691 by @oscarbenjamin)

This will be added to https://github.com/sympy/sympy/wiki/Release-Notes-for-1.11.

Click here to see the pull request description that was parsed.

<!-- Your title above should be a short description of what
was changed. Do not include the issue number in the title. -->

#### References to other Issues or PRs
<!-- If this pull request fixes an issue, write "Fixes #NNNN" in that exact
format, e.g. "Fixes #1234" (see
https://tinyurl.com/auto-closing for more information). Also, please
write a comment on that issue linking back to this pull request once it is
open. -->

Fixes #23318

#### Brief description of what is fixed or changed

Properly handle all factors of a factorisable equation in solveset. Previously the equation was factored but the separate factors were not subsequently solved.

#### Other comments


#### Release Notes

<!-- Write the release notes for this release below between the BEGIN and END
statements. The basic format is a bulleted list with the name of the subpackage
and the release note for this PR. For example:

* solvers
  * Added a new solver for logarithmic equations.

* functions
  * Fixed a bug with log of integers.

or if no release note(s) should be included use:

NO ENTRY

See https://github.com/sympy/sympy/wiki/Writing-Release-Notes for more
information on how to write release notes. The bot will check your release
notes automatically to see if they are formatted correctly. -->

<!-- BEGIN RELEASE NOTES -->
* solvers
  * A bug preventing solveset from properly handling equations that can be factored was fixed.
<!-- END RELEASE NOTES -->

Update

The release notes on the wiki have been updated.

[github-actions]

Benchmark results from GitHub Actions

Lower numbers are good, higher numbers are bad. A ratio less than 1
means a speed up and greater than 1 means a slowdown. Green lines
beginning with + are slowdowns (the PR is slower then master or
master is slower than the previous release). Red lines beginning
with - are speedups.

Significantly changed benchmark results (PR vs master)

Significantly changed benchmark results (master vs previous release)

       before           after         ratio
     [77f1d79c]       [39d5b7df]
     <sympy-1.10.1^0>                 
+         140±3ms          251±5ms     1.79  sum.TimeSum.time_doit

Full benchmark results can be found as artifacts in GitHub Actions
(click on checks at the top of the PR).

[oscarbenjamin]

This is waiting for review.

This is a fix for a regression in 1.10 which is a release blocker.

[oscargus]

Looks good!

[oscarbenjamin]

Thanks!