Fixed issue #15810 and added test for #5547

[smichr]

References to other Issues or PRs

Fixes #15810
Closes #5547 (added tests, fixed elsewhere)
closes #22061 with suggestion from @jksuom implemented

Brief description of what is fixed or changed

For constant gcds, the result was wrong.

Other comments

Release Notes

• integrals
  • Minor fix in case of constant gcd in Risch.

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• integrals
  • Minor fix in case of constant gcd in Risch. (#22283 by @oscargus and @smichr)

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#### References to other Issues or PRs
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Fixes #15810
Closes #5547 (added tests, fixed elsewhere)
closes #22061 with suggestion from @jksuom implemented
#### Brief description of what is fixed or changed
For constant gcds, the result was wrong.

#### Other comments


#### Release Notes

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  * Added a new solver for logarithmic equations.

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* integrals
   * Minor fix in case of constant gcd in Risch.
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Update

The release notes on the wiki have been updated.