URLs without anchors do not have checksums

bin/ruby-build

@@ -204,9 +204,10 @@ fetch_tarball() {
   local package_name="$1"
   local package_url="$2"
   local mirror_url
+  local checksum
 
-  local checksum="${package_url#*\#}"
-  if [ -n "$checksum" ]; then
+  if [ "$package_url" != "${package_url/\#}" ]; then
+    checksum="${package_url#*#}"
     package_url="${package_url%%#*}"
 
     if [ -n "$RUBY_BUILD_MIRROR_URL" ]; then