brew: brew cannot fetch subversion over HTTPS on Mojave

• are reporting a bug others will be able to reproduce and not asking a question
• ran a brew command and reproduced the problem with multiple formulae?
• ran brew update and can still reproduce the problem?
• ran brew doctor, fixed all issues and can still reproduce the problem?
• ran brew config and brew doctor and included their output with your issue?

On Mojave, brew fetch --retry spim --build-bottle --force fails with:

==> Cloning https://svn.code.sf.net/p/spimsimulator/code
==> Checking out 712
svn: E170013: Unable to connect to a repository at URL 'https://svn.code.sf.net/p/spimsimulator/code'
svn: E230001: Server SSL certificate verification failed: issuer is not trusted

The same is true of other formulas using https://svn.code.sf.net/. The certificate looks fine, however: