--compatibility avoids compressing group metadata

closes #403

src/cmd_parser.c

@@ -204,7 +204,7 @@ static GOptionEntry cmd_entries[] =
       "Discard all additional metadata (not primary, filelists and other xml or sqlite files, "
       "nor their compressed variants) from source repository during update.", NULL },
     { "compatibility", 0, 0, G_OPTION_ARG_NONE, &(_cmd_options.compatibility),
-      "Enforce maximal compatibility with classical createrepo (Changes --retain-old-md behavior, uses Gzip for compression, produces sqlite metadata by default).", NULL },
+      "Enforce maximal compatibility with classical createrepo and yum (Changes --retain-old-md behavior, uses Gzip for compression, produces sqlite metadata by default, leaves group metadata uncompressed).", NULL },
     { "retain-old-md-by-age", 0, 0, G_OPTION_ARG_STRING, &(_cmd_options.retain_old_md_by_age),
       "During --update, remove all files in repodata/ which are older "
       "then the specified period of time. (e.g. '2h', '30d', ...). "

src/createrepo_c.c

@@ -853,7 +853,12 @@ main(int argc, char **argv)
 
     // Groupfile specified as argument
     if (cmd_options->groupfile_fullpath) {
-        gchar *compressed_path = cr_compress_groupfile(cmd_options->groupfile_fullpath, tmp_out_repo, compression);
+        cr_CompressionType group_compression = compression;
+        // Skip compressing the group metadata when using --compatibility flag
+        if (cmd_options->compatibility) {
+            group_compression = CR_CW_NO_COMPRESSION;
+        }
+        gchar *compressed_path = cr_compress_groupfile(cmd_options->groupfile_fullpath, tmp_out_repo, group_compression);
         cr_Metadatum *new_groupfile_metadatum = g_malloc0(sizeof(cr_Metadatum));
         new_groupfile_metadatum->name = compressed_path;
         new_groupfile_metadatum->type = g_strdup("group");