Fix version satisfier for unpinned dependencies (#74)

README.md

@@ -21,6 +21,12 @@ Puffin's limited scope allows us to solve many of the low-level problems that ar
 build such a package manager (like package installation) while shipping an immediately useful tool
 with a minimal barrier to adoption. Try it today in lieu of `pip` and `pip-tools`.
 
+## Features
+
+- Extremely fast dependency resolution and installation: install dependencies in sub-second time.
+- Disk-space efficient: Puffin uses a global cache to deduplicate dependencies, and uses
+  Copy-on-Write on supported filesystems to reduce disk usage.
+
 ## Limitations
 
 Puffin does not yet support:

crates/pep508-rs/src/lib.rs

@@ -304,16 +304,14 @@ impl Requirement {
 impl Requirement {
     /// Returns `true` if the [`Version`] satisfies the [`Requirement`].
     pub fn is_satisfied_by(&self, version: &Version) -> bool {
-        let Some(specifiers) =
+        let Some(version_or_url) = self.version_or_url.as_ref() else {
-            self.version_or_url
+            return true;
-                .as_ref()
+        };
-                .and_then(|version_or_url| match version_or_url {
+
-                    VersionOrUrl::VersionSpecifier(specifiers) => Some(specifiers),
+        let specifiers = match version_or_url {
-                    // TODO(charlie): Support URL dependencies.
+            VersionOrUrl::VersionSpecifier(specifiers) => specifiers,
-                    VersionOrUrl::Url(_) => None,
+            // TODO(charlie): Support URL dependencies.
-                })
+            VersionOrUrl::Url(_) => return false,
-        else {
-            return false;
         };
 
         specifiers