search-patches patch not found error

[Alexis Simon]

Hi,

Would anyone know reasons for a patch to not be found in a package 
definition?

I have this source:
-------
(source
     (origin
       (method git-fetch)
       (uri (git-reference
              (url "https://github.com/PalamaraLab/arg-needle-lib.git";)
              (commit (string-append "v" version))))
       (file-name (git-file-name name version))
       (sha256
        (base32 "0zzgbmbn4r8iaihvb2bha7ppz6568bzlzngdzp3cpry38j49z10j"))
       (patches (search-patches 
"patches/python-arg-needle-lib-pybind11.patch"))))
------

And the file exists in patches/python-arg-needle-lib-pybind11.patch

but I get the error
"guix build: error: patches/python-arg-needle-lib-pybind11.patch: patch 
not found"

Alternatively, if I specify the path directly
(patches (list "patches/python-arg-needle-lib-pybind11.patch"))
This works well but I get a warning
guix/packages.scm:997:7: warning: resolving 
'patches/python-arg-needle-lib-pybind11.patch' relative to current directory

Thanks,
Alexis