bug#78649: (recursive? #t) doesn't seem to be part of the source hash

[nomike (they/them)]

Hi!

I'm currently working on a package definition and again stumbled upon an 
issue:

I had the flag `(recursive? #t)` added to `source`:

```scheme
      (source
       (origin
         (method git-fetch)
         (uri (git-reference
               (url "https://github.com/openscad/openscad";)
               (commit commit)
               (recursive? #t)))
         (sha256
          (base32 "1bkzrjjp0qvfg7pj24j5pa0i6zj0zsqjb5z4w3l6pjdb5q9in0qi"))
         (file-name (git-file-name name version))))
```

I then removed the recursive flag and continued on working on my 
package, which is based on a commit-ID of the upstream project. Once I 
switched to a newer commit, I got strange build errors from cmake. I 
switched back the original commit, everything worked again.
It took me a while to remember, that in such a case, guix is not 
re-downloading the source as the source hash doesn't change.

IMHO this hash should also contain flags like recursive.

When  `git clone foo` is changed to `git clone --recursive foo` the 
source has obviously changed (unless the repo doesn't have submodules 
perhaps), so it doesn't make sense that the sha256 hash stays the same.

Is this something we can address?

Or is this an issue as it would invalidate all current source hashes at 
once?

Thanks

nomike