#
  # NOTE: This procedure returns non-zero if the specified package can be
  #       downloaded, i.e. because it is not required for the downloading
  #       process itself to be functional, etc.  The package argument is
  #       the name of the package to check.
  #
  proc canDownloadPackage { package } {
    variable verboseUnknownResult

    #
    # NOTE: Since all the functionality needed by this package is built-in
    #       to Eagle, there are no download restrictions when it is being
    #       used.
    #
    if {[isEagle]} then {
      return true
    }

    #
    # NOTE: Since the "http" and "tls" packages are required from within
    #       the custom [package unknown] itself, in order to locate and
    #       download the requested package, we must return false here to
    #       prevent needless recursion.
    #
    if {[lsearch -exact [list http tls] $package] != -1} then {
      #
      # NOTE: Emit a diagnostic message as this is a relatively rare and
      #       fairly serious issue.
      #
      if {$verboseUnknownResult} then {
        pkgLog [appendArgs \
            "cannot download package \"" $package \
            "\", because it is needed in order to enable downloads"]
      }

      return false
    }

    #
    # NOTE: Currently, all other packages, including Garuda, are legal to
    #       handle from the custom [package unknown] handler.
    #