Why bump consumers? There seems to be no need in that.

I just was not sure when it's actually needed. Could you, please, explain it to me?

The release changed the patch version and according to pkg-plist the shared library version wasn't bumped. This usually means that there is no need to recompile consumers, thus no bumps needed.

This may seems so as I used dynamic SOVERSION. If it wasn't the case the diff would be:
-lib/libz3.so.4.15.3.0
+lib/libz3.so.4.15.4.0

May be unlike major-/minor-level changes just patch-level changes are safe without dependencies bump?
I don't like to do more work than actually needed :) Just need to know which changes are/aren't safe...
Whether it's safe for me to use dynamic SOVERSION at all? (as one wouldn't be able to see actual .so version change)

What does readelf -d /usr/local/lib/libz3.so | grep SONAME say for the updated port?

In D53474#1220993, @arrowd wrote:

What does readelf -d /usr/local/lib/libz3.so | grep SONAME say for the updated port?

0x000000000000000e SONAME Library soname: [libz3.so.4.15]

Seems like I've got it: no actual SONAME change, so no need to update the dependencies. OK.

@yuri: Could you, please, review this? I can't commit it without your signature :)

It'd be great to finally land this.

Sure! Just all my mentors are busy now so I'm waiting for their review...