Fix pre-release exclusive comparison operator in uv-pep440 (#12836)

From PEP 440:

> The exclusive ordered comparison <V MUST NOT allow a pre-release of
the specified version unless the specified version is itself a
pre-release. Allowing pre-releases that are earlier than, but not equal
to a specific pre-release may be accomplished by using <V.rc1 or
similar.

We had an additional check that would block this even if the specifier
did have a pre-release.

This likely didn't show up earlier because `Ranges` uses different code
in the resolver.

I checked these changes against `packaging` to verify their behavior:

```python
print(SpecifierSet("<1").contains("1a1", prereleases=True)) # False
print(SpecifierSet("<1a2").contains("1a1", prereleases=True)) # True
print(SpecifierSet("<1").contains("1dev1", prereleases=True)) # False
print(SpecifierSet("<1dev2").contains("1dev1", prereleases=True)) # True
print(SpecifierSet("<1a2").contains("1dev1", prereleases=True)) # True
```

Closes #12834

crates/uv-pep440/src/version_specifier.rs

@@ -554,16 +554,9 @@ impl VersionSpecifier {
                 other.as_ref() >= this
             }
             Operator::GreaterThan => Self::greater_than(this, &other),
-            Operator::GreaterThanEqual => {
-                Self::greater_than(this, &other) || other.as_ref() >= this
-            }
-            Operator::LessThan => {
-                Self::less_than(this, &other)
-                    && !(version::compare_release(&this.release(), &other.release())
-                        == Ordering::Equal
-                        && other.any_prerelease())
-            }
-            Operator::LessThanEqual => Self::less_than(this, &other) || other.as_ref() <= this,
+            Operator::GreaterThanEqual => other.as_ref() >= this,
+            Operator::LessThan => Self::less_than(this, &other),
+            Operator::LessThanEqual => other.as_ref() <= this,
         }
     }
 
@@ -572,13 +565,13 @@ impl VersionSpecifier {
             return true;
         }
 
-        // This special case is here so that, unless the specifier itself
-        // includes is a pre-release version, that we do not accept pre-release
-        // versions for the version mentioned in the specifier (e.g. <3.1 should
-        // not match 3.1.dev0, but should match 3.0.dev0).
-        if !this.any_prerelease()
-            && other.is_pre()
-            && version::compare_release(&this.release(), &other.release()) == Ordering::Equal
+        // The exclusive ordered comparison <V MUST NOT allow a pre-release of the specified
+        // version unless the specified version is itself a pre-release. E.g., <3.1 should
+        // not match 3.1.dev0, but should match both 3.0.dev0 and 3.0, while <3.1.dev1 does match
+        // 3.1.dev0, 3.0.dev0 and 3.0.
+        if version::compare_release(&this.release(), &other.release()) == Ordering::Equal
+            && !this.any_prerelease()
+            && other.any_prerelease()
         {
             return false;
         }
@@ -1172,10 +1165,15 @@ mod tests {
             ("2.0.1", ">2"),
             ("2.1.post1", ">2"),
             ("2.1+local.version", ">2"),
+            ("2.post2", ">2.post1"),
             // Test the less than operation
             ("1", "<2"),
             ("2.0", "<2.1"),
             ("2.0.dev0", "<2.1"),
+            // https://github.com/astral-sh/uv/issues/12834
+            ("0.1a1", "<0.1a2"),
+            ("0.1dev1", "<0.1dev2"),
+            ("0.1dev1", "<0.1a1"),
             // Test the compatibility operation
             ("1", "~=1.0"),
             ("1.0.1", "~=1.0"),
@@ -1271,6 +1269,7 @@ mod tests {
             ("2.0c1.post1.dev1", ">2"),
             ("2.0rc1", ">2"),
             ("2.0", ">2"),
+            ("2.post2", ">2"),
             ("2.0.post1", ">2"),
             ("2.0.post1.dev1", ">2"),
             ("2.0+local.version", ">2"),