503 on projects Settings/Repository / "Rugged::InvalidError: failed to parse signature - malformed e-mail"

Summary

When I open Settings/Repository on a certain project I get a 503 response.

Steps to reproduce

This problem occurs on one specfic repository which unfortunately I cannot make public. I this project I go to Setting/Repository. I can supply output needed for diagnostics.

What is the current bug behavior?

503 error page, log entries shown below.

What is the expected correct behavior?

Show repository settings page.

Relevant logs and/or screenshots

Gitaly log:

level=error msg="finished streaming call" error="rpc error: code = Unknown desc = Rugged::InvalidError: failed to parse signature - malformed e-mail" grpc.code=Unknown grpc.meta.client_name=gitlab-web grpc.method=FindAllTags grpc.request.glRepository=project-79 grpc.request.repoPath=abc/xyz.git grpc.request.repoStorage=default grpc.request.topLevelGroup=abc grpc.service=gitaly.RefService grpc.time_ms=4 peer.address=@ span.kind=server system=grpc

Production.log (procect names changed)

Started GET "/abc/xyz/settings/repository" for 172.31.42.246 at 2018-09-17 09:52:05 +0000
Processing by Projects::Settings::RepositoryController#show as HTML
  Parameters: {"namespace_id"=>"abc", "project_id"=>"xyz"}

Gitlab::Git::CommandError (2:Rugged::InvalidError: failed to parse signature - malformed e-mail):
  lib/gitlab/git/repository.rb:1017:in `rescue in wrapped_gitaly_errors'
  lib/gitlab/git/repository.rb:1010:in `wrapped_gitaly_errors'
  lib/gitlab/git/repository.rb:210:in `tags'
  app/models/repository.rb:749:in `tags'
  app/models/protectable_dropdown.rb:25:in `public_send'
  app/models/protectable_dropdown.rb:25:in `refs'
  app/models/protectable_dropdown.rb:29:in `ref_names'
  app/models/protectable_dropdown.rb:15:in `protectable_ref_names'
  app/models/protectable_dropdown.rb:19:in `hash'
  app/controllers/projects/settings/repository_controller.rb:66:in `protectable_tags_for_dropdown'
  app/controllers/projects/settings/repository_controller.rb:74:in `load_gon_index'
  app/controllers/projects/settings/repository_controller.rb:43:in `define_protected_refs'
  app/controllers/projects/settings/repository_controller.rb:28:in `render_show'
  app/controllers/projects/settings/repository_controller.rb:8:in `show'
  lib/gitlab/i18n.rb:51:in `with_locale'
  lib/gitlab/i18n.rb:57:in `with_user_locale'
  app/controllers/application_controller.rb:401:in `set_locale'
  lib/gitlab/middleware/multipart.rb:97:in `call'
  lib/gitlab/request_profiler/middleware.rb:14:in `call'
  lib/gitlab/middleware/go.rb:17:in `call'
  lib/gitlab/etag_caching/middleware.rb:11:in `call'
  lib/gitlab/middleware/read_only/controller.rb:38:in `call'
  lib/gitlab/middleware/read_only.rb:16:in `call'
  lib/gitlab/middleware/basic_health_check.rb:25:in `call'
  lib/gitlab/request_context.rb:18:in `call'
  lib/gitlab/metrics/requests_rack_middleware.rb:27:in `call'
  lib/gitlab/middleware/release_env.rb:10:in `call'

Completed 503 Service Unavailable in 34ms (Views: 1.0ms | ActiveRecord: 5.9ms)

Output of checks

(If you are reporting a bug on GitLab.com, write: This bug happens on GitLab.com)

Results of GitLab environment info

System information
System:		Ubuntu 16.04
Current User:	git
Using RVM:	no
Ruby Version:	2.4.4p296
Gem Version:	2.7.6
Bundler Version:1.16.2
Rake Version:	12.3.1
Redis Version:	3.2.11
Git Version:	2.18.0
Sidekiq Version:5.1.3
Go Version:	unknown


GitLab information
Version:	11.2.3
Revision:	06cbee3
Directory:	/opt/gitlab/embedded/service/gitlab-rails
DB Adapter:	postgresql
URL:		https://gitlab.xyz.de
HTTP Clone URL:	https://gitlab.xyz.de/some-group/some-project.git
SSH Clone URL:	git@gitlab.xyz.de:some-group/some-project.git
Using LDAP:	yes
Using Omniauth:	no


GitLab Shell
Version:	8.1.1
Repository storage paths:
  • default: /var/opt/gitlab/git-data/repositories Hooks: /opt/gitlab/embedded/service/gitlab-shell/hooks Git: /opt/gitlab/embedded/bin/git

Results of GitLab application Check

Expand for output related to the GitLab application check 
Checking GitLab Shell ...


GitLab Shell version >= 8.1.1 ? ... OK (8.1.1)
Repo base directory exists?
default... yes
Repo storage directories are symlinks?
default... no
Repo paths owned by git:root, or git:git?
default... yes
Repo paths access is drwxrws---?
default... yes
hooks directories in repos are links: ...
7/1 ... ok
8/2 ... ok
8/3 ... ok
... (All ok or "repository is empty", repository in question is ok)


Running /opt/gitlab/embedded/service/gitlab-shell/bin/check
Check GitLab API access: OK
Redis available via internal API: OK


Access to /var/opt/gitlab/.ssh/authorized_keys: OK
gitlab-shell self-check successful


Checking GitLab Shell ... Finished


Checking Sidekiq ...


Running? ... yes
Number of Sidekiq processes ... 1


Checking Sidekiq ... Finished


Reply by email is disabled in config/gitlab.yml
Checking LDAP ...


Server: ldapmain
LDAP authentication... Success
LDAP users with access to your GitLab server (only showing the first 100 results)
... (List of users)
Checking LDAP ... Finished


Checking GitLab ...


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: ...
7/1 ... yes
8/2 ... yes
8/3 ... yes
... (all yes)
Redis version >= 2.8.0? ... yes
Ruby version >= 2.3.5 ? ... yes (2.4.4)
Git version >= 2.9.5 ? ... yes (2.18.0)
Git user has default SSH configuration? ... yes
Active users: ... 19


Checking GitLab ... Finished

Possible fixes

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