Respect default umask in distribution archive (#2023)

When copying files from the nix store to the intermediate directory,
ignore the source file permissions. These are coming from the nix store,
so they will not be writable.

Without this change, this will result in unexpected `Permission denied`
when manipulating extracted files.

Fixes: #2022

Author: sgillespie

flake.nix

@@ -406,6 +406,7 @@
                     # Copy exes to intermediate dir
                     cp \
                       --no-clobber \
+                      --no-preserve=mode \
                       --remove-destination \
                       --verbose \
                       ${lib.concatMapStringsSep " " (exe: "${exe}/bin/*") exes} \
@@ -414,6 +415,7 @@
                     # Copy magrations to intermediate dir
                     cp \
                       --no-clobber \
+                      --no-preserve=mode \
                       --remove-destination \
                       --verbose \
                       --recursive \