How to downgrade subversion to version 1.7 I'm on OS Sierra.

I currently have subversion 1.9 and I want to downgrade to 1.7.

I tried this so far with no luck:

$ brew tap homebrew/versions
$ brew install subversion17
Error: No available formula with the name "subversion17" 
==&gt; Searching for similarly named formulae...
Error: No similarly named formulae found.
==&gt; Searching taps...
Error: No formulae found in taps.
$ brew search subversion
homebrew/versions/subversion18   


What other options might I have?

Edit:  More background:

I'm getting this message when I run svn commands in my working directory:


&gt; svn: E155036: Please see the 'svn upgrade' command svn: E155036: The
&gt; working copy at '/Users/MyProject' is too old (format 29) to work with
&gt; client version '1.9.4 (r1740329)' (expects format 31). You need to
&gt; upgrade the working copy first.



I'm worried if I run the upgrade I won't be able to talk to the server anymore?  And I have no control over what version the server is running and I don't think they would be willing to upgrade it.
Whatever your underlying motivation or use case is: I personally recommended that you do not downgrade. Downgrading to Subversion 1.7 will put your Mac at risk.

Also, for technical reasons, Subversion 1.7 cannot run on El Capitan or later unless a developer is willing to spend considerable effort.

The subversion17 formula was deleted from Homebrew last month, albeit for unrelated reasons. Before it got deleted, a comment in the formula said:


  # Requires system OpenSSL headers to build. &gt;El Capitan no longer ship them.
  # Note this means that this subversion is linked against an outdated OpenSSL
  # and really should not be considered secure.


In other words, not only is Subversion 1.7 unsafe to use on macOS; also, El Capitan or later versions of macOS cannot run 1.7 because the required header files are missing.

For the same reason, well-known Subversion download sources, e. g. WANdisco’s download page, offer Subversion 1.7 releases for OS X Yosemite or earlier but not for current macOS versions.

An alternative approach would be that you post a new question (or edit your existing one) to give more information on what your underlying motivation is.


What are you actually trying to achieve specifically with the 1.7 release?
What specific issue(s) do you anticipate, or have already encountered, using the latest release of Subversion instead, or any other version control package?