Redmine

I noticed this error in yesterday, but I don't know since I have it
however, the problem is that some repositories are not updated, others are ok
I tried to update from 2.6.5 to 2.6.6 but nothing changes

my about:

Environment:
  Redmine version                2.6.6.stable
  Ruby version                   1.9.3-p484 (2013-11-22) [x86_64-linux]
  Rails version                  3.2.22
  Environment                    production
  Database adapter               Mysql2
SCM:
  Subversion                     1.8.8
  Git                            1.9.1
  Filesystem
Redmine plugins:
  redmine_charts2                0.2.1
  redmine_code_review            0.6.3
  redmine_contacts               3.4.4
  redmine_custom_css             0.1.4
  redmine_jstoolbar_ext          0.2.0
  redmine_jstoolbar_ext_coderay  0.1.0
  redmine_jstoolbar_ext_images   0.1.0
  redmine_lightbox2              0.1.3
  redmine_people                 0.1.8
  redmine_release_notes          1.3.1
  redmine_wiki_extensions        0.6.5

and some parts of production.log:

Started GET "/projects/bbox/repository" for 192.168.10.196 at 2015-09-18 21:40:59 +0200
Processing by RepositoriesController#show as HTML
  Parameters: {"id"=>"bbox"}
  Setting Load (0.2ms)  SELECT `settings`.* FROM `settings` WHERE `settings`.`name` = 'session_lifetime' LIMIT 1
  Setting Load (0.2ms)  SELECT `settings`.* FROM `settings` WHERE `settings`.`name` = 'session_timeout' LIMIT 1
   (0.2ms)  SELECT MAX(`settings`.`updated_on`) AS max_id FROM `settings`
  User Load (0.3ms)  SELECT `users`.* FROM `users` WHERE `users`.`type` IN ('User', 'AnonymousUser') AND `users`.`status` = 1 AND `users`.`id` = 19 LIMIT 1
  Current user: mauro (id=19)
   (0.1ms)  SELECT MAX(`contacts_settings`.`updated_on`) AS max_id FROM `contacts_settings`
  Setting Load (0.1ms)  SELECT `settings`.* FROM `settings` WHERE `settings`.`name` = 'force_default_language_for_loggedin' LIMIT 1
  Project Load (0.1ms)  SELECT `projects`.* FROM `projects` WHERE `projects`.`identifier` = 'bbox' LIMIT 1
  Repository Load (0.1ms)  SELECT `repositories`.* FROM `repositories` WHERE `repositories`.`project_id` = 1 AND (is_default = 1) LIMIT 1
Shelling out: 'git' --version --no-color
Shelling out: 'git' '--git-dir' '/srv/git/bbox.git' '-c' 'core.quotepath=false' '-c' 'log.decorate=no' 'branch' '--no-color' '--verbose' '--no-abbrev'
  SQL (0.1ms)  SELECT `enabled_modules`.`name` FROM `enabled_modules` WHERE `enabled_modules`.`project_id` = 1
  Setting Load (0.1ms)  SELECT `settings`.* FROM `settings` WHERE `settings`.`name` = 'autofetch_changesets' LIMIT 1
   (0.1ms)  SELECT COUNT(*) FROM `changesets` WHERE `changesets`.`repository_id` = 32
Shelling out: 'git' '--git-dir' '/srv/git/bbox.git' '-c' 'core.quotepath=false' '-c' 'log.decorate=no' 'log' '--no-color' '--encoding=UTF-8' '--raw' '--date=iso' '--pretty=fuller' '--parents' '--stdin' '--reverse'
git log error: git exited with non-zero status: 128