mkdir -p $depfile crashes with fatal: cycle in rule variables: depfile -> depfile

[infinity0]

rule cat
  depfile = d
  command = $
   mkdir -p "$$(dirname $depfile)"; $
   mkdir -p "$$(dirname $out)"; $
   cat $in > $out; $
   touch $depfile

build c: cat /dev/null

$ ninja -f lol.ninja c
ninja: fatal: cycle in rule variables: depfile -> depfile

Error remains even if you comment out the mkdir -p $depfile line.

Error goes away if you REMOVE that line.

Behaviour is very counterintuitive - wasted hours debugging thinking it was to do with complex depfile behaviour, when it was just this dumb unrelated thing. Seems like ninja-build is scanning command including comments to look for undeclared dependencies, and has an exception for $out but not $depfile???

$ ninja --version
1.11.1
$ apt-cache policy ninja-build
[..]
 *** 1.11.1-1 990
        990 http://deb.debian.org/debian testing/main amd64 Packages
[..]

[digit-google]

FWIW, this was fixed by PR #2291, which will be part of the next 1.12 release