handle deps with git+ssh locations

[gilligan]

I have a project which uses several private modules which are not on npms but just git repos. So npm2nix will fail with something like :

building path(s) ‘/nix/store/z0dnfrb0riii8mgzg9k7mdfh3i7gpgbq-healthcheck-middleware-e288c34’
exporting ssh://[email protected]/dragon/healthcheck-middleware.git (rev e288c349675d4a2fbfd9e0c194797bbaa7377406) into /nix/store/z0dnfrb0riii8mgzg9k7mdfh3i7gpgbq-healthcheck-middleware-e288c34
Initialized empty Git repository in /nix/store/z0dnfrb0riii8mgzg9k7mdfh3i7gpgbq-healthcheck-middleware-e288c34/.git/
error: cannot run ssh: No such file or directory
fatal: unable to fork
error: cannot run ssh: No such file or directory
fatal: unable to fork
Unable to checkout e288c349675d4a2fbfd9e0c194797bbaa7377406 from ssh://[email protected]/dragon/healthcheck-middleware.git.
builder for ‘/nix/store/jmrypk071qp14z0q9crbz3ij1s3x6h0c-healthcheck-middleware-e288c34.drv’ failed with exit code 1
building path(s) ‘/nix/store/hkw9rj95qd5sqws7nlw0bg80yin2r9z2-hoist-non-react-statics-1.0.2.tgz’
cannot build derivation ‘/nix/store/ilcpj8lsv4h9mjk5pdf2za9hg0jimq0q-nodejs-healthcheck-middleware-1.0.0.drv’: 1 dependencies couldn't be built
cannot build derivation ‘/nix/store/fy0hiahnlvqjfk0ynq5nbmqiwbgmzi9v-nodejs-infrastructure-0.7.2.drv’: 1 dependencies couldn't be built
killing process 12934
cannot build derivation ‘/nix/store/zzvrm0xxnizryhixq1aakssk7y7kda9f-nodejs-hc-react-stack-pages-0.0.0.drv’: 1 dependencies couldn't be built
error: build of ‘/nix/store/zzvrm0xxnizryhixq1aakssk7y7kda9f-nodejs-hc-react-stack-pages-0.0.0.drv’ failed

Can this be supported at all ? And if not could you provide some info on a possible workaround for this scenario ?