Address name conflicts

[stevendborrelli]

If two resources have the same name an error is not raised. In testing the 2nd task defined is used.

task "a" {
   check = "[[ -d /tmp/a ]]"
   apply = "mkdir /tmp/a"
}

task "a" {
   check = "[[ -d /tmp/b ]]"
   apply = "mkdir /tmp/b"
}

[ryane]

This hcl also can also result in some user confusion:

task "c" {
  check = "[[ -d /tmp/c ]]"
  apply = "mkdir /tmp/c"
}

task "d" {
  check = "[[ -d /tmp/c ]]"
  apply = "mkdir /tmp/c"
}

It is the same task with different names but you'll never see the duplicate in your graph.

MergeDuplicates explicitly handles both of these scenarios and you can identify when it happens if you are running with log-level=debug. Should we just change the logging to Warn with a clearer message or should we actually consider one or both of these as errors and stop execution?

[arichardet]

Fixed by #458