fix(curl): Do not reuse URL from previous call

Previously the URL could be accidentally reused between requests.

    local curl = require "plenary.curl"
    curl.get("url", { dry_run = true }) -- { ..., "-X", "GET", "url" }
    curl.get({ dry_run = true })        -- { ..., "-X", "GET", "url" }

Author: juntuu

lua/plenary/curl.lua

@@ -332,9 +332,9 @@ end
 -- Main ----------------------------------------------------
 ------------------------------------------------------------
 return (function()
-  local spec = {}
   local partial = function(method)
     return function(url, opts)
+      local spec = {}
       opts = opts or {}
       if type(url) == "table" then
         opts = url

tests/plenary/curl_spec.lua

@@ -202,4 +202,20 @@ describe("CURL Wrapper:", function()
       assert(type(res) == "table")
     end)
   end)
+
+  describe("Issue #601", function() --------------------------------------------
+    it("should not use URL from previous call", function()
+      local url = "https://example.com"
+      local opts = { dry_run = true, dump = "" } -- dump would be random each time
+      local first = curl.get(url, opts)
+      eq(table.remove(first, #first), url, "expected url last")
+
+      local success, second = pcall(curl.get, opts)
+      if success then
+        eq(first, second, "should be same, but without url")
+      else
+        -- Failure is also acceptable
+      end
+    end)
+  end)
 end)