tic80 behaves differently when run from source checkout

[technomancy]

I've built the pro version of TIC80 in my ~/src/tic80/build directory. Then I've copied the tic80 executable from build/bin/tic80 into ~/bin/tic80. When I do this, it can no longer load text carts any more:

$ sha1sum ~/bin/tic80
e46d19a6141b5a702ad77667a6b750ad726e13fa  /home/phil/bin/tic80
$ sha1sum ../tic80/build/bin/tic80 # they're the same contents
e46d19a6141b5a702ad77667a6b750ad726e13fa  ../tic80/build/bin/tic80
$ ~/bin/tic80 --cli --cmd "load tower.fnl"

file not found$ # oops; error message is missing newline
$ ../tic80/build/bin/tic80 --cli --cmd "load tower.fnl"

cart tower.fnl loaded!
use RUN command to run it

However, the copy in my ~/bin directory seems to have no trouble loading .tic carts. It seems that maybe moving it out of the source tree causes it to forget that it's a pro build?

The latest stable tag (v1.1.2837) does not appear to be affected by this problem, but git main does.