title: http.get() returns "422 Unprocessable Entity"
body: <p>I have written a go programme to query issues in github repository "golang:go".
  The http.Get() responds with status  "200 OK".
  I then query for issues created in last 3 months and the http.Get() returns "422 Unprocessable Entity". Below is the programme  </p>
  
  <pre><code>import(
          "fmt"
          "time"
          "net/http"
          "net/url"
          )
  
  func main() {
          var ret error
          var str string 
  
          q:=url.QueryEscape("repo:golang/go")
          fmt.Println("q:", q)
          urlStr := "https://api.github.com/search/issues" +"?q=" + q 
          fmt.Println("urlStr:", urlStr)
          resp, ret:= http.Get(urlStr)
          fmt.Println("ret :", ret, "resp.status :", resp.Status)
  
          timeStr := "created:"
          to := time.Now()
          from := to.AddDate(0, -3, 0)
  
          str = to.Format("2006-01-02")
          timeStr = timeStr + str + ".."
          fmt.Printf("time1 : %s\n", timeStr)
  
          str = from.Format("2006-01-02")
          timeStr = timeStr + str 
          fmt.Printf("time2 : %s\n", timeStr)
  
          q=url.QueryEscape("repo:golang/go" + timeStr)
          fmt.Println("q:", q)
          urlStr = "https://api.github.com/search/issues" +"?q=" + q 
          fmt.Println("urlStr:", urlStr)
          resp, ret = http.Get(urlStr)
          fmt.Println("ret :", ret, "resp.status :", resp.Status) 
  }   
  </code></pre>
  
  <p>I used <a href="https://developer.github.com/v3/search/#search-issues" rel="nofollow noreferrer">this</a> to form the query.</p>
  
  <p>I am new to web programming and not able to understand where I went wrong in forming the second query.</p>