many: unify boolean env var handling

logger/logger.go

@@ -27,6 +27,8 @@ import (
 	"log/syslog"
 	"os"
 	"sync"
+
+	"github.com/snapcore/snapd/osutil"
 )
 
 // A Logger is a fairly minimal logging tool.
@@ -109,7 +111,7 @@ func (l *ConsoleLog) Debug(msg string) {
 	s := "DEBUG: " + msg
 	l.sys.Output(3, s)
 
-	if os.Getenv("SNAPD_DEBUG") != "" {
+	if osutil.EnvBool("SNAPD_DEBUG") {
 		l.log.Output(3, s)
 	}
 }