Increase MAX_ACCEPTABLE_VARIABLES_COUNT to 20

Currently, the ParseDotenvArtifactService has a hardcoded limit
of 10 parsed variables per dotenv file. This change increases that
to 20.

app/services/ci/parse_dotenv_artifact_service.rb

@@ -3,7 +3,7 @@
 module Ci
   class ParseDotenvArtifactService < ::BaseService
     MAX_ACCEPTABLE_DOTENV_SIZE = 5.kilobytes
-    MAX_ACCEPTABLE_VARIABLES_COUNT = 10
+    MAX_ACCEPTABLE_VARIABLES_COUNT = 20
 
     SizeLimitError = Class.new(StandardError)
     ParserError = Class.new(StandardError)

changelogs/unreleased/increase-dotenv-variable-count.yml

+---
+title: increase allowed dotenv variables from 10 to 20
+merge_request: 45815
+author: jrreid
+type: changed

doc/ci/pipelines/job_artifacts.md

@@ -114,7 +114,9 @@ There are a couple of exceptions to the [original dotenv rules](https://github.c
 
 - The variable key can contain only letters, digits, and underscores (`_`).
 - The maximum size of the `.env` file is 5 KB.
-- The maximum number of variables is 10.
+- In GitLab 13.5 and older, the maximum number of inherited variables is 10.
+- In [GitLab 13.6 and later](https://gitlab.com/gitlab-org/gitlab/-/issues/247913),
+  the maximum number of inherited variables is 20.
 - Variable substitution in the `.env` file is not supported.
 - The `.env` file can't have empty lines or comments (starting with `#`).
 - Key values in the `env` file cannot have spaces or newline characters (`\n`), including when using single or double quotes.