Avoid double encoding of import url credentials

Import projects by URL, when the URLs credentials have characters that
require percent encoding, is currently not working. This feature is
failing because the import url credentials are being encoded before
saving on the database, on the `Project#import_url=`, and then it's
being encoded again when retrieving the credentials from the database,
on `Project#import_url`.

To solve the problem the credential is being percent decoded before
saving it on the database.

app/models/project.rb

@@ -901,7 +901,9 @@ class Project < ApplicationRecord
     if Gitlab::UrlSanitizer.valid?(value)
       import_url = Gitlab::UrlSanitizer.new(value)
       super(import_url.sanitized_url)
-      create_or_update_import_data(credentials: import_url.credentials)
+
+      credentials = import_url.credentials.to_h.transform_values { |value| CGI.unescape(value.to_s) }
+      create_or_update_import_data(credentials: credentials)
     else
       super(value)
     end

changelogs/unreleased/avoid-double-credential-encoding-on-project-importing.yml

+---
+title: Avoid double encoding of credential while importing a Project by URL
+merge_request: 24514
+author:
+type: fixed

spec/models/project_spec.rb

@@ -1980,6 +1980,23 @@ describe Project do
 
       expect(project.reload.import_url).to eq('http://test.com')
     end
+
+    it 'saves the url credentials percent decoded' do
+      url = 'http://user:pass%21%3F%40@github.com/t.git'
+      project = build(:project, import_url: url)
+
+      # When the credentials are not decoded this expectation fails
+      expect(project.import_url).to eq(url)
+      expect(project.import_data.credentials).to eq(user: 'user', password: 'pass!?@')
+    end
+
+    it 'saves url with no credentials' do
+      url = 'http://github.com/t.git'
+      project = build(:project, import_url: url)
+
+      expect(project.import_url).to eq(url)
+      expect(project.import_data.credentials).to eq(user: nil, password: nil)
+    end
   end
 
   describe '#container_registry_url' do