sccache and sccache-overlay

Hello hackers@

I'm trying to work out why sccache/sccache-overlay will sometimes fail 
for a pkg in poudriere-devel like this:

###
[00:00:13] ===>  Configuring for icu-73.1,1
[00:00:13] ==> Starting sccache
[00:00:13] sccache: Starting the server...
[00:00:23] sccache: error: Timed out waiting for server startup
[00:00:23] sccache: error: No such file or directory (os error 2)
[00:00:23] *** Error code 2
[00:00:23] 
[00:00:23] Stop.
[00:00:23] make: stopped in /usr/ports/devel/icu
[00:00:25] =>> Cleaning up wrkdir
[00:00:25] ===>  Cleaning for icu-73.1,1
###

Running poudriere again, and the problem is gone and the pkg builds fine.
sccache-overlay is installed as per 'pkg info -D sccache-overlay'

There's no man page yet for either sccache-overlay or sccache, so
am at a loss as to how to debug.

thanks in advance for any clue
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