trurl: handle zero length query pairs

Added several new test cases for it

Fixes #387
Reported-by: joveian on github

Author: bagder

tests.json

@@ -3274,5 +3274,49 @@
             "stderr": "trurl error: --json is mutually exclusive with --get\ntrurl error: Try trurl -h for help\n",
             "returncode": 4
         }
+    },
+    {
+        "input": {
+            "arguments": [
+                "e?e&&"
+            ]
+        },
+        "expected": {
+            "stdout": "http://e/?e\n",
+            "returncode": 0
+        }
+    },
+    {
+        "input": {
+            "arguments": [
+                "e?e&"
+            ]
+        },
+        "expected": {
+            "stdout": "http://e/?e\n",
+            "returncode": 0
+        }
+    },
+    {
+        "input": {
+            "arguments": [
+                "e?e&&&&&&&&&&&&&&&&&&&&&"
+            ]
+        },
+        "expected": {
+            "stdout": "http://e/?e\n",
+            "returncode": 0
+        }
+    },
+    {
+        "input": {
+            "arguments": [
+                "e?e&&&&&&&&&&a&&&&&&&&&&&"
+            ]
+        },
+        "expected": {
+            "stdout": "http://e/?e&a\n",
+            "returncode": 0
+        }
     }
 ]

trurl.c

@@ -1572,8 +1572,8 @@ static void qpair2query(CURLU *uh, struct option *o)
   for(i = 0; i<nqpairs; i++) {
     char *oldnq = nq;
     nq = curl_maprintf("%s%s%s", nq ? nq : "",
-                       (nq && *nq && *(qpairs[i].str)) ? o->qsep : "",
-                       qpairs[i].str);
+                       (nq && *nq && qpairs[i].len) ? o->qsep : "",
+                       qpairs[i].len ? qpairs[i].str : "");
     curl_free(oldnq);
   }
   if(nq) {