container: Allow alternative formatting to drop ostree-unverified-registry

Since
ostreedev/ostree-rs-ext@34fea14
we are backing off the signature verification bits.  Let's make
it easier to not put those bits in the user's face by
adding an alternative formatting that drops it if it's the default.

Author: cgwalters

lib/src/container/mod.rs

@@ -31,6 +31,7 @@ use ostree::glib;
 
 use std::borrow::Cow;
 use std::collections::HashMap;
+use std::fmt::Debug;
 use std::ops::Deref;
 use std::str::FromStr;
 
@@ -277,7 +278,14 @@ impl std::fmt::Display for OstreeImageReference {
             (SignatureSource::ContainerPolicyAllowInsecure, imgref)
                 if imgref.transport == Transport::Registry =>
             {
-                write!(f, "ostree-unverified-registry:{}", self.imgref.name)
+                // Because allow-insecure is the effective default, allow formatting
+                // without it.  Note this formatting is asymmetric and cannot be
+                // re-parsed.
+                if f.alternate() {
+                    write!(f, "{}", self.imgref)
+                } else {
+                    write!(f, "ostree-unverified-registry:{}", self.imgref.name)
+                }
             }
             (sigverify, imgref) => {
                 write!(f, "{}:{}", sigverify, imgref)
@@ -584,10 +592,8 @@ mod tests {
         assert_eq!(ir.sigverify, SignatureSource::ContainerPolicy);
         assert_eq!(ir.imgref.transport, Transport::Registry);
         assert_eq!(ir.imgref.name, "quay.io/exampleos/blah");
-        assert_eq!(
-            ir.to_string(),
-            "ostree-image-signed:docker://quay.io/exampleos/blah"
-        );
+        assert_eq!(ir.to_string(), ir_s);
+        assert_eq!(format!("{:#}", &ir), ir_s);
 
         let ir_s = "ostree-unverified-image:docker://quay.io/exampleos/blah";
         let ir: OstreeImageReference = ir_s.try_into().unwrap();
@@ -602,6 +608,7 @@ mod tests {
             OstreeImageReference::try_from("ostree-unverified-registry:quay.io/exampleos/blah")
                 .unwrap();
         assert_eq!(&ir_shorthand, &ir);
+        assert_eq!(format!("{:#}", &ir), "docker://quay.io/exampleos/blah");
     }
 
     #[test]