Filter out useless bundler output from std-in

filter.go

package main

import (
  "os"
  "bufio"
  "fmt"
  "regexp"
)

func main() {
  input := bufio.NewScanner(os.Stdin)
  for input.Scan() {
    usingMatch, _ := regexp.MatchString("^Using", input.Text())
    fetchingSourceMatch, _ := regexp.MatchString("^Fetching source index", input.Text())
    fetchingGemMatch, _ := regexp.MatchString("^Fetching gem metadata", input.Text())
    finalLineMatch, _ := regexp.MatchString("to see where a bundled gem is installed\.$", input.Text())

    if !usingMatch && !fetchingSourceMatch && !fetchingGemMatch && !finalLineMatch {
      fmt.Println(input.Text())
    }
  }
}