Fix CommitLinter to allow subjects that start with a capital letter

Signed-off-by: Rémy Coutable <remy@rymai.me>

lib/gitlab/danger/commit_linter.rb

@@ -180,6 +180,8 @@ module Gitlab
       end
 
       def subject_starts_with_lowercase?
+        return false if ('A'..'Z').cover?(subject[0])
+
         first_char = subject.sub(/\A(\[.+\]|\w+:)\s/, '')[0]
         first_char_downcased = first_char.downcase
         return true unless ('a'..'z').cover?(first_char_downcased)

spec/lib/gitlab/danger/commit_linter_spec.rb

@@ -192,7 +192,9 @@ RSpec.describe Gitlab::Danger::CommitLinter do
         '[Ci skip] A commit message',
         '[API] A commit message',
         'api: A commit message',
-        'API: A commit message'
+        'API: A commit message',
+        'API: a commit message',
+        'API: a commit message'
       ].each do |message|
         context "when subject is '#{message}'" do
           let(:commit_message) { message }
@@ -209,8 +211,6 @@ RSpec.describe Gitlab::Danger::CommitLinter do
         '[ci skip]A commit message',
         '[Ci skip]  A commit message',
         '[ci skip] a commit message',
-        'API: a commit message',
-        'API: a commit message',
         'api: a commit message',
         '! A commit message'
       ].each do |message|