Fix issue with empty host tree in hosts.toml

Signed-off-by: Brad Davidson <brad.davidson@rancher.com>

remotes/docker/config/hosts.go

@@ -376,11 +376,6 @@ func parseHostsFile(baseDir string, b []byte) ([]hostConfig, error) {
 		HostConfigs map[string]hostFileConfig `toml:"host"`
 	}{}
 
-	orderedHosts, err := getSortedHosts(tree)
-	if err != nil {
-		return nil, err
-	}
-
 	var (
 		hosts []hostConfig
 	)
@@ -389,15 +384,24 @@ func parseHostsFile(baseDir string, b []byte) ([]hostConfig, error) {
 		return nil, err
 	}
 
-	// Parse hosts array
-	for _, host := range orderedHosts {
-		config := c.HostConfigs[host]
-
-		parsed, err := parseHostConfig(host, baseDir, config)
+	// The HostConfigs map is unordered, so we need to return the hosts sorted by
+	// line number in the file to honor the order requested by the user.
+	if len(c.HostConfigs) > 0 {
+		orderedHosts, err = getSortedHosts(tree)
 		if err != nil {
 			return nil, err
 		}
-		hosts = append(hosts, parsed)
+
+		// Parse hosts array
+		for _, host := range orderedHosts {
+			config := c.HostConfigs[host]
+
+			parsed, err := parseHostConfig(host, baseDir, config)
+			if err != nil {
+				return nil, err
+			}
+			hosts = append(hosts, parsed)
+		}
 	}
 
 	// Parse root host config and append it as the last element