When graphics/librsvg2 was updated to 2.40.20 (May 2018), there was a stray assignment PORTREVISON=1. That's a typo (SON instead of SION). But it did not need PORTREVISION set to 1 anyway. So it's harmless. But next time this is updated (latest upstream version is 2.44), please remove the bogus PORTREVISON line.
A commit references this bug: Author: koobs Date: Wed Nov 14 03:56:42 UTC 2018 New revision: 484912 URL: https://svnweb.freebsd.org/changeset/ports/484912 Log: graphics/librsvg2: Remove PORTREVISON (typo) variable ports r470310 updated graphics/librsvg2 (PORTVERSION) to 2.40.20, but also included a typo'd PORTREVISION variable, with a value of 1, in the change. Since the PORTVERSION was updated, incrementing the PORTREVISION was not necessary as the updated package would have been built without it. Since the typo'd variable is not included in PKGNAME version calculation, it is a noop. Remove the variable accordingly. PR: 233214 Reported by: John Hein <z7dr6ut7gs snkmail com> Approved by: portmgr (just fix it) MFH: 2018Q4 Changes: head/graphics/librsvg2/Makefile
Missed merge window, ports r484912 now exists in quarterly