fix(provider): leave provider specifications to user (#887)

* add(settings): dont_set_python_host_prog option

* fix(provider): leave provider specifications to user

* remove unused code

---------

Co-authored-by: Jint-lzxy <50296129+Jint-lzxy@users.noreply.github.com>

lua/core/options.lua

@@ -103,18 +103,22 @@ local function load_options()
 		wrapscan = true,
 		writebackup = false,
 	}
+
 	local function isempty(s)
 		return s == nil or s == ""
 	end
+	local function use_if_defined(val, fallback)
+		return val ~= nil and val or fallback
+	end
 
 	-- custom python provider
 	local conda_prefix = os.getenv("CONDA_PREFIX")
 	if not isempty(conda_prefix) then
-		vim.g.python_host_prog = conda_prefix .. "/bin/python"
-		vim.g.python3_host_prog = conda_prefix .. "/bin/python"
+		vim.g.python_host_prog = use_if_defined(vim.g.python_host_prog, conda_prefix .. "/bin/python")
+		vim.g.python3_host_prog = use_if_defined(vim.g.python3_host_prog, conda_prefix .. "/bin/python")
 	else
-		vim.g.python_host_prog = "python"
-		vim.g.python3_host_prog = "python3"
+		vim.g.python_host_prog = use_if_defined(vim.g.python_host_prog, "python")
+		vim.g.python3_host_prog = use_if_defined(vim.g.python3_host_prog, "python3")
 	end
 
 	for name, value in pairs(global_local) do