pep440: support post/local for semver allows

This change ensures that post and local releases are taken into
consideration when checking if semver version instance allows
post and local build releases.

The following conditions now hold `poetry.core.semver.Version.allows`.

- `3.0.0` allows `3.0.0+local.1`, `3.0.0-1`
- `3.0.0+local.1` disallows `3.0.0+local.2`, allows `3.0.0-1`
- `3.0.0-1` disallows ``3.0.0`, `3.0.0+local.1`, allows `3.0.0-1+local.1`

poetry/core/semver/version.py

@@ -80,10 +80,26 @@ def is_empty(self) -> bool:
         return False
 
     def allows(self, version: "Version") -> bool:
-        return self == version
+        _this, _other = self, version
+
+        # allow weak equality to allow `3.0.0+local.1` for `3.0.0`
+        if not _this.is_local() and _other.is_local():
+            _other = _other.without_local()
+        elif _this.is_local() and not _other.is_local():
+            _this = _this.without_local()
+
+        # allow weak equality to allow `3.0.0-1` for `3.0.0`
+        if not _this.is_postrelease() and _other.is_postrelease():
+            _other = _other.without_postrelease()
+        elif _this.without_postrelease() and not _other.without_postrelease():
+            _this = _this.without_postrelease()
+
+        return _this == _other
 
     def allows_all(self, other: "VersionTypes") -> bool:
-        return other.is_empty() or other == self
+        return other.is_empty() or (
+            self.allows(other) if isinstance(other, self.__class__) else other == self
+        )
 
     def allows_any(self, other: "VersionTypes") -> bool:
         return other.allows(self)
@@ -101,15 +117,15 @@ def union(self, other: "VersionTypes") -> "VersionTypes":
             return other
 
         if isinstance(other, VersionRangeConstraint):
-            if other.min == self:
+            if self.allows(other.min):
                 return VersionRange(
                     other.min,
                     other.max,
                     include_min=True,
                     include_max=other.include_max,
                 )
 
-            if other.max == self:
+            if self.allows(other.max):
                 return VersionRange(
                     other.min,
                     other.max,

tests/semver/test_version.py

@@ -113,7 +113,29 @@ def test_allows():
     assert not v.allows(Version.parse("1.3.3"))
     assert not v.allows(Version.parse("1.2.4"))
     assert not v.allows(Version.parse("1.2.3-dev"))
-    assert not v.allows(Version.parse("1.2.3+build"))
+    assert v.allows(Version.parse("1.2.3+build"))
+    assert v.allows(Version.parse("1.2.3-1"))
+    assert v.allows(Version.parse("1.2.3-1+build"))
+
+
+def test_allows_with_local():
+    v = Version.parse("1.2.3+build.1")
+    assert v.allows(v)
+    assert not v.allows(Version.parse("1.3.3"))
+    assert not v.allows(Version.parse("1.2.3-dev"))
+    assert not v.allows(Version.parse("1.2.3+build.2"))
+    assert v.allows(Version.parse("1.2.3-1"))
+    assert v.allows(Version.parse("1.2.3-1+build.1"))
+
+
+def test_allows_with_post():
+    v = Version.parse("1.2.3-1")
+    assert v.allows(v)
+    assert not v.allows(Version.parse("1.2.3"))
+    assert not v.allows(Version.parse("2.2.3"))
+    assert not v.allows(Version.parse("1.2.3-dev"))
+    assert not v.allows(Version.parse("1.2.3+build.2"))
+    assert v.allows(Version.parse("1.2.3-1+build.1"))
 
 
 def test_allows_all():