fix(pep440): handle v-prefixed versions gracefully (renovatebot#40989)

* fix(pep440): handle v-prefixed versions gracefully

* Retain v-prefix

* Fix test coverage and use named group

Author: felipecrs

lib/modules/versioning/pep440/index.spec.ts

@@ -101,6 +101,8 @@ describe('modules/versioning/pep440/index', () => {
     currentValue            | rangeStrategy    | currentVersion | newVersion   | expected
     ${'1.0.0'}              | ${'bump'}        | ${'1.0.0'}     | ${'1.2.3'}   | ${'1.2.3'}
     ${'1.0.0'}              | ${'replace'}     | ${'1.0.0'}     | ${'1.2.3'}   | ${'1.2.3'}
+    ${'v1.0.0'}             | ${'bump'}        | ${'1.0.0'}     | ${'1.2.3'}   | ${'v1.2.3'}
+    ${'v1.0.0'}             | ${'replace'}     | ${'1.0.0'}     | ${'1.2.3'}   | ${'v1.2.3'}
     ${'==1.0.3'}            | ${'bump'}        | ${'1.0.0'}     | ${'1.2.3'}   | ${'==1.2.3'}
     ${'==1.0.3'}            | ${'replace'}     | ${'1.0.0'}     | ${'1.2.3'}   | ${'==1.2.3'}
     ${'>=1.2.0'}            | ${'bump'}        | ${'1.0.0'}     | ${'1.2.3'}   | ${'>=1.2.3'}

lib/modules/versioning/pep440/range.spec.ts

@@ -35,4 +35,24 @@ describe('modules/versioning/pep440/range', () => {
     );
     expect(logger.warn).not.toHaveBeenCalled();
   });
+
+  it('handles v-prefixed version as currentValue', () => {
+    const res = getNewValue({
+      currentValue: 'v0.7.15',
+      rangeStrategy: 'auto',
+      newVersion: '0.8.0',
+      currentVersion: '0.7.15',
+    });
+    expect(res).toBe('v0.8.0');
+  });
+
+  it('handles bare version that differs from currentVersion without v-prefix', () => {
+    const res = getNewValue({
+      currentValue: '1.0.0.0',
+      rangeStrategy: 'auto',
+      newVersion: '1.2.3',
+      currentVersion: '1.0.0',
+    });
+    expect(res).toBe('1.2.3');
+  });
 });

lib/modules/versioning/pep440/range.ts

@@ -117,6 +117,17 @@ export function getNewValue({
     return newVersion;
   }
 
+  // Handle bare versions (e.g., "v0.7.15") that don't strictly equal
+  // currentVersion due to normalization, treating them as pinned while
+  // preserving the v-prefix.
+  if (parseVersion(currentValue)) {
+    const vPrefix = regEx(/^(?<prefix>[vV])/).exec(currentValue);
+    if (vPrefix) {
+      return `${vPrefix.groups!.prefix}${newVersion}`;
+    }
+    return newVersion;
+  }
+
   try {
     ranges = parseCurrentRange(currentValue);
     if (!ranges.length) {