Hopefully fixes #110149. I'm really annoyed with this on 21.05 now: https://hydra.nixos.org/build/147005675#tabs-buildsteps and this isn't the first time it's caused significant issues.
···11+Use full bash's sh in tests instead of /bin/sh, as that would be
22+too minimalist in the build sandbox. See issue:
33+https://github.com/NixOS/nixpkgs/issues/110149#issuecomment-874258128
44+diff --git a/test/extracttest b/test/extracttest
55+--- a/test/extracttest
66++++ b/test/extracttest
77+@@ -9,2 +9,3 @@ setupTests() {
88+ $SUT $* archive makeself-test.run "Test $*" echo Testing
99++ sed "1s|/bin|$(dirname "$SHELL")|" -i ./makeself-test.run
1010+ }