Fake a JSON module to make --pretend work without kde-build-metadata.

This is mostly to make the testsuite run, which is not supposed to pull
down kde-build-metadata, though it may be worth it to construct a
suitable "fake metadata" instead.

modules/ksb/Updater/KDEProjectMetadata.pm

@@ -49,7 +49,8 @@ sub logicalModuleGroups
     my $self = shift;
     my $path = $self->module()->fullpath('source') . "/logical-module-structure";
 
-    my $fh = pretend_open($path) or
+    # The {} is an empty JSON obj to support pretend mode
+    my $fh = pretend_open($path, '{}') or
         croak_internal("Unable to read logical module structure: $!");
 
     my ($json_hashref, $e) = do {
@@ -61,7 +62,7 @@ sub logicalModuleGroups
         ($json, $@); # Implicit return
     };
 
-    croak_runtime ("Unable to load module group data! :(\n\t$e") if $e;
+    croak_runtime ("Unable to load module group data from $path! :(\n\t$e") if $e;
     return $json_hashref;
 }
 

modules/ksb/Util.pm

@@ -628,6 +628,7 @@ sub download_file
 #
 # Parameters:
 #  filename - Path to the file to open.
+#  default  - String to use if the file doesn't exist in pretend mode
 #
 # Returns:
 #  filehandle on success (supports readline() and eof()), can return boolean
@@ -636,11 +637,11 @@ sub download_file
 sub pretend_open
 {
     my $path = shift;
+    my $defaultText = shift // '';
     my $fh;
 
     if (pretending() && ! -e $path) {
-        my $simulatedFile = '';
-        open $fh, '<', \$simulatedFile or return;
+        open $fh, '<', \$defaultText or return;
     }
     else {
         open $fh, '<', $path or return;