add --skip=check/signed-by

mmdebstrap

@@ -5117,17 +5117,17 @@ sub main() {
             # a signed-by option
             my $signedby        = '';
             my %suite_by_vendor = get_suite_by_vendor();
-            {
+            my $gpgproc         = sub {
                 my $keyring
                   = get_keyring_by_suite($options->{suite}, \%suite_by_vendor);
                 if (!defined $keyring) {
-                    last;
+                    return '';
                 }
 
                 # we can only check if we need the signed-by entry if we u
                 # automatically chosen keyring exists
                 if (!defined $keyring || !-e $keyring) {
-                    last;
+                    return '';
                 }
 
                 # we can only check key material if gpg is installed
@@ -5155,9 +5155,9 @@ sub main() {
                     close $fh;
                 }
                 if ($? != 0 || !defined $ret || defined $message) {
-                    info "gpg --version failed: cannot determine the right"
-                      . " signed-by value";
-                    last;
+                    warning
+                      "gpg --version failed: cannot infer signed-by value";
+                    return '';
                 }
                 # initialize gpg trustdb with empty one
                 {
@@ -5166,7 +5166,7 @@ sub main() {
                 }
                 if (!-d $options->{apttrustedparts}) {
                     warning "$options->{apttrustedparts} doesn't exist";
-                    last;
+                    return '';
                 }
                 # find all the fingerprints of the keys apt currently
                 # knows about
@@ -5188,8 +5188,7 @@ sub main() {
                 }
                 my @aptfingerprints = ();
                 if (scalar @keyrings == 0) {
-                    $signedby = " [signed-by=\"$keyring\"]";
-                    last;
+                    return " [signed-by=\"$keyring\"]";
                 }
                 info "Finding correct signed-by value...";
                 my $progress = 0.0;
@@ -5212,8 +5211,7 @@ sub main() {
                 }
                 print_progress("done");
                 if (scalar @aptfingerprints == 0) {
-                    $signedby = " [signed-by=\"$keyring\"]";
-                    last;
+                    return " [signed-by=\"$keyring\"]";
                 }
                 # check if all fingerprints from the keyring that we guessed
                 # are known by apt and only add signed-by option if that's not
@@ -5229,15 +5227,20 @@ sub main() {
                         # if this fingerprint is not known by apt, then we need
                         #to add the signed-by option
                         if (none { $_ eq $1 } @aptfingerprints) {
-                            $signedby = " [signed-by=\"$keyring\"]";
-                            last;
+                            return " [signed-by=\"$keyring\"]";
                         }
                     }
                     close $fh;
+                    if ($? != 0) {
+                        warning "gpg failed -- cannot infer signed-by value";
+                    }
                 }
-                if ($? != 0) {
-                    error "gpg failed";
-                }
+                return '';
+            };
+            if (any { $_ eq 'check/signed-by' } @{ $options->{skip} }) {
+                info "skipping check/signed-by as requested";
+            } else {
+                $signedby = $gpgproc->();
             }
             if (scalar @ARGV > 0) {
                 for my $arg (@ARGV) {
@@ -6943,6 +6946,8 @@ Upon startup, several checks are carried out, like:
 
 =item * whether the output directory is empty. This check can be disabled using B<--skip=check/empty>
 
+=item * whether adding a C<signed-by> to C<apt/sources.list> is necessary. This requires gpg and can be disabled using B<--skip=check/signed-by>
+
 =back
 
 =item B<setup>