tests: usage_vs_refs.sh: fix false failure with Alpine

* tests/misc/usage_vs_refs.sh: Fix missing escape on literal {,
required by busybox grep.
Reported by Bruno Haible.

diff --git a/tests/misc/usage_vs_refs.sh b/tests/misc/usage_vs_refs.sh
index ebb132a68ba545c026269e9460a34cc2478aee78..6e5a43f2185fd0501c4ddbc3814abb004a25414b 100755 (executable)
--- a/tests/misc/usage_vs_refs.sh
+++ b/tests/misc/usage_vs_refs.sh
@@ -53,7 +53,7 @@ for prg in $built_programs; do
   got_option=false
   for opt in $(getopts $prg); do
     got_option=true
-    if ! grep -E "opt(Itemx?|Anchor){$dprg,$opt[,}]" \
+    if ! grep -E "opt(Itemx?|Anchor)\\{$dprg,$opt[,}]" \
           "$abs_top_srcdir/doc/coreutils.texi" >/dev/null; then
       if ! grep "optItemx\\?{\\\\cmd\\\\,$opt," \
             "$abs_top_srcdir/doc/coreutils.texi" >/dev/null; then