elevate the fix for 'None' string literals into a general rule

This is very safe to do in the general case since ""None"" is very
obviously a JSON syntax error, and having it here next to where the
problem is caused is clearer than having a special override in a
completely different place.

internal/collector/recon/sharding.go

@@ -15,7 +15,6 @@
 package recon
 
 import (
-	"bytes"
 	"encoding/json"
 	"fmt"
 
@@ -527,12 +526,6 @@ func (t *ShardingTask) UpdateMetrics() (map[string]int, error) {
 	}
 
 	for hostname, dataBytes := range outputPerHost {
-		if !json.Valid(dataBytes) {
-			//Replace instances of breaking null string errors with a 0.
-			//Workaround for unmarshalling, and consistent with eventual metric export value. (0: no error/1: error)
-			dataBytes = bytes.ReplaceAll(dataBytes, []byte(`"None"`), []byte(`0`))
-		}
-
 		var data struct {
 			ShardingStats ShardingStats `json:"sharding_stats"`
 		}
@@ -593,7 +586,7 @@ func (t *ShardingTask) UpdateMetrics() (map[string]int, error) {
 			t.containerShardingInProgressActive.With(l).Set(float64(shardingProcess.Active))
 			t.containerShardingInProgressCleaved.With(l).Set(float64(shardingProcess.Cleaved))
 			t.containerShardingInProgressCreated.With(l).Set(float64(shardingProcess.Created))
-			if shardingProcess.Error != `0` {
+			if shardingProcess.Error != "None" {
 				t.containerShardingInProgressError.With(l).Set(float64(1))
 			} else {
 				t.containerShardingInProgressError.With(l).Set(float64(0))

internal/collector/recon/utils.go

@@ -90,12 +90,15 @@ func splitOutputPerHost(output []byte, cmdArgs []string) (map[string][]byte, err
 
 		logg.Debug("output from command 'swift-recon %s': %s: %s", util.CmdArgsToStr(cmdArgs), hostname, string(data))
 
-		// sanitize JSON
+		// convert Python literals to JSON (best effort)
 		data = bytes.ReplaceAll(data, []byte(`u'`), []byte(`'`))
 		data = bytes.ReplaceAll(data, []byte(`'`), []byte(`"`))
 		data = bytes.ReplaceAll(data, []byte(`True`), []byte(`true`))
 		data = bytes.ReplaceAll(data, []byte(`False`), []byte(`false`))
 		data = bytes.ReplaceAll(data, []byte(`None`), []byte(`"None"`))
+		data = bytes.ReplaceAll(data, []byte(`""None""`), []byte(`"None"`))
+		//^ We sometimes observe strings with the value "None".
+		//The None -> "None" replacement introduces double quoting there which we need to compensate for.
 
 		//In the event that object store issues add escape characters to swift-recon output, strip these chracters to continue.
 		data = []byte(stripEscapeChars(string(data)))