Merge branch 'maint'

* maint:
docs: describe behavior of relative submodule URLs
fix hang in git fetch if pointed at a 0 length bundle
Documentation: read-tree --prefix works with existing subtrees
Add MYMETA.json to perl/.gitignore

diff --combined bundle.c
index 4742f2734eeb3dee117ab02a422056cfee4f71ea,8a1d53ba29a434139123bd7d4e37db47ba8728cb..b8acf3c18b600f1f413f95744ad281e3879b3f6e
--- 1/bundle.c
--- 2/bundle.c
+++ b/bundle.c
@@@ -31,8 -31,8 +31,8 @@@ static int strbuf_readline_fd(struct st
        while (1) {
                char ch;
                ssize_t len = xread(fd, &ch, 1);
-               if (len < 0)
-                       return -1;
+               if (len <= 0)
+                       return len;
                strbuf_addch(sb, ch);
                if (ch == '\n')
                        break;
@@@ -320,7 -320,7 +320,7 @@@ int create_bundle(struct bundle_header 
                        continue;
                if (dwim_ref(e->name, strlen(e->name), sha1, &ref) != 1)
                        continue;
 -              if (!resolve_ref(e->name, sha1, 1, &flag))
 +              if (read_ref_full(e->name, sha1, 1, &flag))
                        flag = 0;
                display_ref = (flag & REF_ISSYMREF) ? e->name : ref;