Currently py-scipy fails to build in gitlab ci, due the following:

• py-pythran generates 256 include dirs, which are set as a colon-seperated string in the SPACK_INCLUDE_DIRS environment variable;
• due to install path padding each path is at least 512 bytes in size

This results in a string of at least 128KB, which is at least MAX_ARG_STRLEN = 32 * PAGE_SIZE = 32 * 4KB = 128KB.

And this makes exec syscalls fail, since they have a limit on the argument length (env variables are just arguments after argv):

https://github.com/torvalds/linux/blob/49da070062390094112b423ba443ea193527b2e4/fs/exec.c#L291-L294

https://github.com/torvalds/linux/blob/49da070062390094112b423ba443ea193527b2e4/fs/exec.c#L535-L541

resulting in E2BIG or Argument list too long, which is the build error we see.