Don't prefer HTTPs repository URL by default

The one used in Git repository (e.g., SSH) works better with
unregistered packages.

src/api.jl

@@ -159,10 +159,13 @@ in `Manifest.toml` file checked in its repository (e.g.,
 - `project::Union{Nothing, AbstractString} = nothing`: Project
   in which the package is installed.  `nothing` (default) means
   the current activated project.
+- `prefer_https::Bool = false`: Prefer HTTPS repository URL rather
+  than the one used in Git repository.
 """
 function add(
     name::AbstractString;
     project::Union{Nothing, AbstractString} = nothing,
+    prefer_https::Bool = false,
 )
     path = joinpath(expanduser("~/.julia/dev"), name)  # TODO: don't
     @assert isdir(path)
@@ -177,7 +180,7 @@ function add(
         return (rank, r)
     end
     manifestfile, = sort(find_manifests(path), by=sortkey)
-    spec = pkgspecof(path)
+    spec = pkgspecof(path; prefer_https=prefer_https)
     deps = keys(get(
         TOML.parsefile(projecttomlpath(path)),
         "deps",

src/utils.jl

@@ -12,9 +12,13 @@ function pkgat(path::AbstractString) :: PkgId
     return PkgId(UUID(prj["uuid"]), prj["name"])
 end
 
-function pkgspecof(path::AbstractString)
+function pkgspecof(path::AbstractString; prefer_https=false)
     prj = TOML.parsefile(projecttomlpath(path))
-    url = vcslinktoroot(path=path)
+    if prefer_https
+        url = vcslinktoroot(path=path)
+    else
+        url = strip(read(git_cmd(`config remote.origin.url`, path), String))
+    end
     tree_sha = strip(read(git_cmd(`rev-parse "HEAD^{tree}"`, path), String))
     spec = Pkg.PackageSpec(
         name = prj["name"],