fix(manager/conan): allow ref with user only

lib/modules/manager/conan/__fixtures__/conanfile.py

@@ -3,7 +3,7 @@
 class Pkg(ConanFile):
    python_requires = "pyreq/0.1@user/channel"  # recipe to reuse code from
    build_requires = "tool_a/0.2@user/testing", "tool_b/0.2@user/testing"
-   requires = "req_a/1.0", "req_l/2.1@otheruser/testing"
+   requires = "req_a/1.0", "req_l/2.1@otheruser/testing", "req_x/6.1@useronly"
 
    requires = [("req_b/0.1@user/testing"),
                ("req_d/0.2@dummy/stable", "override"),

lib/modules/manager/conan/extract.spec.ts

@@ -152,6 +152,13 @@ describe('modules/manager/conan/extract', () => {
           packageName: 'req_l/2.1@otheruser/testing',
           replaceString: 'req_l/2.1@otheruser/testing',
         },
+        {
+          currentValue: '6.1',
+          depName: 'req_x',
+          depType: 'requires',
+          packageName: 'req_x/6.1@useronly/_',
+          replaceString: 'req_x/6.1@useronly',
+        },
         {
           currentValue: '0.1',
           depName: 'req_b',

lib/modules/manager/conan/extract.ts

@@ -4,7 +4,7 @@ import type { PackageDependency, PackageFileContent } from '../types';
 import { isComment } from './common';
 
 const regex = regEx(
-  `(?<name>[-_a-z0-9]+)/(?<version>[^@\n{*"']+)(?<userChannel>@[-_a-zA-Z0-9]+/[^#\n.{*"' ]+)?#?(?<revision>[-_a-f0-9]+[^\n{*"'])?`,
+  `(?<name>[-_a-z0-9]+)/(?<version>[^@\n{*"']+)(?<userChannel>@[-_a-zA-Z0-9]+(?:/[^#\n.{*"' ]+|))?#?(?<revision>[-_a-f0-9]+[^\n{*"'])?`,
 );
 
 function setDepType(content: string, originalType: string): string {
@@ -52,6 +52,9 @@ export function extractPackageFile(content: string): PackageFileContent | null {
             if (matches.groups.userChannel) {
               userAndChannel = matches.groups.userChannel;
               replaceString = `${depName}/${currentValue}${userAndChannel}`;
+              if (!userAndChannel.includes('/')) {
+                userAndChannel = `${userAndChannel}/_`;
+              }
             }
             const packageName = `${depName}/${currentValue}${userAndChannel}`;