External users can't access internal project repositories as guests

Summary

In the project member permissions documentation, it notes that Guest users can view project code, pull project code, and download projects on public and internal projects.

If you grant an external user guest permissions on an internal project, the user cannot view project code, pull project code, or download the project.

From the documentation, these permissions should be supported. If this is the case, there is a bug in the permissions logic for external users.

Reported by an Ultimate SMB Premium customer --> https://gitlab.zendesk.com/agent/tickets/157549 (internal use only)

Steps to reproduce

1. Create an internal project, Project A
2. Create an external user, User 1
3. Log in as User 1 and access Project A
4. User 1 cannot access the repository in Project A

If User 1 is not external, but just a guest, they can access the repository in Project A. Additionally, if User 1 is external but is a reporter on Project A, they can access the repository.

What is the current bug behavior?

External guest users are not able to access an internal project's repository.

What is the expected correct behavior?

External guest users are able to access an internal project's repository.

Output of checks

Results of GitLab environment info

Expand for output related to GitLab environment info

System information
System:		Ubuntu 16.04
Proxy:		no
Current User:	git
Using RVM:	no
Ruby Version:	2.6.5p114
Gem Version:	2.7.10
Bundler Version:1.17.3
Rake Version:	12.3.3
Redis Version:	5.0.7
Git Version:	2.26.2
Sidekiq Version:5.2.7
Go Version:	unknown

GitLab information
Version:	12.10.1-ee
Revision:	695c29abcf7
Directory:	/opt/gitlab/embedded/service/gitlab-rails
DB Adapter:	PostgreSQL
DB Version:	11.7
URL:		https://blunceford-omnibus-test.do.gitlap.com
HTTP Clone URL:	https://blunceford-omnibus-test.do.gitlap.com/some-group/some-project.git
SSH Clone URL:	git@blunceford-omnibus-test.do.gitlap.com:some-group/some-project.git
Elasticsearch:	yes
Geo:		no
Using LDAP:	yes
Using Omniauth:	yes
Omniauth Providers: azure_oauth2, openid_connect

GitLab Shell
Version:	12.2.0
Repository storage paths:
- default: 	/var/opt/gitlab/git-data/repositories
GitLab Shell path:		/opt/gitlab/embedded/service/gitlab-shell
Git:		/opt/gitlab/embedded/bin/git

Results of GitLab application Check

Expand for output related to the GitLab application check

Checking GitLab subtasks ...
Checking GitLab Shell ...
GitLab Shell: ... GitLab Shell version >= 12.2.0 ? ... OK (12.2.0)
Running /opt/gitlab/embedded/service/gitlab-shell/bin/check
Internal API available: OK
Redis available via internal API: OK
gitlab-shell self-check successful
Checking GitLab Shell ... Finished
Checking Gitaly ...
Gitaly: ... default ... OK
Checking Gitaly ... Finished
Checking Sidekiq ...
Sidekiq: ... Running? ... yes
Number of Sidekiq processes ... 1
Checking Sidekiq ... Finished
Checking Incoming Email ...
Incoming Email: ... Reply by email is disabled in config/gitlab.yml
Checking Incoming Email ... Finished
Checking LDAP ...
LDAP: ... Server: ldapmain
Exception: getaddrinfo: Name or service not known
Checking LDAP ... Finished
Checking GitLab App ...
Git configured correctly? ... yes
Database config exists? ... yes
All migrations up? ... yes
Database contains orphaned GroupMembers? ... no
GitLab config exists? ... yes
GitLab config up to date? ... yes
Log directory writable? ... yes
Tmp directory writable? ... yes
Uploads directory exists? ... yes
Uploads directory has correct permissions? ... yes
Uploads directory tmp has correct permissions? ... yes
Init script exists? ... skipped (omnibus-gitlab has no init script)
Init script up-to-date? ... skipped (omnibus-gitlab has no init script)
Projects have namespace: ...
2/1 ... yes
2/2 ... yes
2/3 ... yes
35/4 ... yes
35/5 ... yes
35/6 ... yes
35/7 ... yes
35/8 ... yes
36/9 ... yes
36/10 ... yes
37/11 ... yes
37/12 ... yes
37/13 ... yes
37/14 ... yes
37/15 ... yes
37/16 ... yes
38/17 ... yes
38/18 ... yes
38/19 ... yes
38/20 ... yes
38/21 ... yes
38/22 ... yes
39/23 ... yes
39/24 ... yes
39/25 ... yes
39/26 ... yes
39/27 ... yes
39/28 ... yes
39/29 ... yes
39/30 ... yes
40/31 ... yes
40/32 ... yes
41/33 ... yes
41/34 ... yes
41/35 ... yes
41/36 ... yes
41/37 ... yes
41/38 ... yes
41/39 ... yes
41/40 ... yes
41/41 ... yes
42/42 ... yes
42/43 ... yes
42/44 ... yes
42/45 ... yes
42/46 ... yes
42/47 ... yes
42/48 ... yes
42/49 ... yes
42/50 ... yes
42/51 ... yes
43/52 ... yes
43/53 ... yes
43/54 ... yes
44/55 ... yes
44/56 ... yes
44/57 ... yes
44/58 ... yes
44/59 ... yes
44/60 ... yes
44/61 ... yes
44/62 ... yes
45/63 ... yes
45/64 ... yes
45/65 ... yes
45/66 ... yes
45/67 ... yes
45/68 ... yes
45/69 ... yes
46/70 ... yes
46/71 ... yes
46/72 ... yes
47/73 ... yes
47/74 ... yes
47/75 ... yes
47/76 ... yes
47/77 ... yes
47/78 ... yes
47/79 ... yes
47/80 ... yes
48/81 ... yes
48/82 ... yes
48/83 ... yes
48/84 ... yes
48/85 ... yes
48/86 ... yes
48/87 ... yes
48/88 ... yes
48/89 ... yes
48/90 ... yes
49/91 ... yes
49/92 ... yes
49/93 ... yes
49/94 ... yes
49/95 ... yes
50/96 ... yes
50/97 ... yes
1/98 ... yes
1/99 ... yes
1/100 ... yes
1/101 ... yes
51/102 ... yes
51/103 ... yes
1/104 ... yes
1/105 ... yes
1/106 ... yes
Redis version >= 4.0.0? ... yes
Ruby version >= 2.5.3 ? ... yes (2.6.5)
Git version >= 2.22.0 ? ... yes (2.26.2)
Git user has default SSH configuration? ... yes
Active users: ... 87
Is authorized keys file accessible? ... yes
Elasticsearch version 5.6 - 6.x? ... yes (7.5.2)
Checking GitLab App ... Finished
Checking GitLab subtasks ... Finished

Possible fixes

(If you can, link to the line of code that might be responsible for the problem)