not sure if this is related, but xpra gives me these errors:

  File "/nix/store/pllrjhhf3swl1pmi5il945sr0lb2gzp9-xpra-4.0.2/bin/xpra", line 2
    export PATH='/nix/store/fjgnz0xfl04hsblsi4ym5y5akfh6mlmy-python3-3.8.5/bin:/nix/store/pllrjhhf3swl1pmi5il945sr0lb2gzp9-xpra-4.0.2/bin:/nix/store/c9w6ij5j1wjcvrzb12j4a4fvfzy1saf6-python3.8-numpy-1.19.1/bin:/nix/store/q24nzpj4lvzvvj2vkgywrsy1xyrskx1y-cairo-1.16.0-dev/bin:/nix/store/iid4kx5h4xw1c8zfl9hbls3w7wl1nc3k-freetype-2.10.2-dev/bin:/nix/store/kxcwjq4sd5iiqgiqp39zqs4pczb1i2kj-bzip2-1.0.6.0.1-bin/bin:/nix/store/im2q3xxm6swqqzmks0vylvyca0zq7jyr-libpng-apng-1.6.37-dev/bin:/nix/store/p6gkd5bc6rsi76mjjjp1zcqahfnnjbg2-fontconfig-2.13.92-bin/bin:/nix/store/f6949p636lzzqck6cvc5hb0gs188ydgi-expat-2.2.8-dev/bin:/nix/store/j81d3idny3bq1z465kbs48in466vws1i-glib-2.64.4-dev/bin:/nix/store/7nf8kal37yngkmb3m2xngfi7hhkf1hcl-gettext-0.21/bin:/nix/store/zgggvc0k23kb2k2vljprpcqmkwbchxwx-glib-2.64.4-bin/bin:/nix/store/q68r74xs1syjf8l4ll34izc6dl0zqxnb-gstreamer-1.16.2-dev/bin:/nix/store/p20m5gj8pf9zld2qls0v7q9c8dm22zy4-gst-plugins-base-1.16.2/bin:/nix/store/bsxg89rp0rc5piznkm5g7j9fv76nvsr9-linux-pam-1.3.1/bin:/nix/store/qwm4i75vvyi41pvzj6cxmwrvzbq7gl5y-opencv-4.3.0/bin'${PATH:+':'}$PATH
           ^
SyntaxError: invalid syntax
^C
got signal SIGINT

not sure if this is related, but xpra gives me these errors:

  File "/nix/store/pllrjhhf3swl1pmi5il945sr0lb2gzp9-xpra-4.0.2/bin/xpra", line 2
    export PATH='/nix/store/fjgnz0xfl04hsblsi4ym5y5akfh6mlmy-python3-3.8.5/bin:/nix/store/pllrjhhf3swl1pmi5il945sr0lb2gzp9-xpra-4.0.2/bin:/nix/store/c9w6ij5j1wjcvrzb12j4a4fvfzy1saf6-python3.8-numpy-1.19.1/bin:/nix/store/q24nzpj4lvzvvj2vkgywrsy1xyrskx1y-cairo-1.16.0-dev/bin:/nix/store/iid4kx5h4xw1c8zfl9hbls3w7wl1nc3k-freetype-2.10.2-dev/bin:/nix/store/kxcwjq4sd5iiqgiqp39zqs4pczb1i2kj-bzip2-1.0.6.0.1-bin/bin:/nix/store/im2q3xxm6swqqzmks0vylvyca0zq7jyr-libpng-apng-1.6.37-dev/bin:/nix/store/p6gkd5bc6rsi76mjjjp1zcqahfnnjbg2-fontconfig-2.13.92-bin/bin:/nix/store/f6949p636lzzqck6cvc5hb0gs188ydgi-expat-2.2.8-dev/bin:/nix/store/j81d3idny3bq1z465kbs48in466vws1i-glib-2.64.4-dev/bin:/nix/store/7nf8kal37yngkmb3m2xngfi7hhkf1hcl-gettext-0.21/bin:/nix/store/zgggvc0k23kb2k2vljprpcqmkwbchxwx-glib-2.64.4-bin/bin:/nix/store/q68r74xs1syjf8l4ll34izc6dl0zqxnb-gstreamer-1.16.2-dev/bin:/nix/store/p20m5gj8pf9zld2qls0v7q9c8dm22zy4-gst-plugins-base-1.16.2/bin:/nix/store/bsxg89rp0rc5piznkm5g7j9fv76nvsr9-linux-pam-1.3.1/bin:/nix/store/qwm4i75vvyi41pvzj6cxmwrvzbq7gl5y-opencv-4.3.0/bin'${PATH:+':'}$PATH
           ^
SyntaxError: invalid syntax
^C
got signal SIGINT

I remember that, it looks like #41106 which I thought we fixed. can you elaborate on what derivation of xpra you are using and what commands you issued?

/nix/store/57w6i6jh5jscq4ns8nnd5hkds975k82h-xpra-4.0.2/bin/xpra I just run it, click on some buttons and get these errors in the terminal. It's against the current master.

The absence of double-wrapping breaks /nix/store/57w6i6jh5jscq4ns8nnd5hkds975k82h-xpra-4.0.2/lib/python3.8/site-packages/xpra/platform/xposix/paths.py:163. This can be mitigated with an environment variable though, so I'll do that.

Ok it's fixed. It wasn't #41106, it was a different regression introduced by this change. I didn't hit it because I use xpra in CLI. Maybe it's better to keep the doublewrapping on account of don't fix it if it ain't broke?