security: Properly initialize state in `SigningInfo(const std::string&)` constructor

Change-Id: Ie5aad142ed6ab0545f6804677e9c8a537ddc9b97
refs: #3365
diff --git a/src/security/signing-info.cpp b/src/security/signing-info.cpp
index 283484b..0872167 100644
--- a/src/security/signing-info.cpp
+++ b/src/security/signing-info.cpp
@@ -40,8 +40,9 @@
 
 SigningInfo::SigningInfo(const std::string& signingStr)
 {
+  *this = SigningInfo();
+
   if (signingStr.empty()) {
-    *this = SigningInfo();
     return;
   }