take at least 1 usedep

src/atom/parsers.rs

@@ -303,7 +303,7 @@ impl<'a> Parseable<'a, &'a str> for Atom {
         let usedeps = || {
             UseDep::parser()
                 .separated_by(tag(","))
-                .many()
+                .at_least(1)
                 .delimited_by(tag("["), tag("]"))
                 .opt()
         };
@@ -552,6 +552,7 @@ mod test {
             "=kde-frameworks/kcodecs-6.19*86",
             "=dev-ml/stdio-0.17*t:=[ocamlopt?]",
             ">=dev-libs/libgee-0-8.5:0..8=",
+            "<dev-haskell/wai-3.3:=[]",
         ];
 
         for atom in atoms {