Merge branch 'dm-bitbucket-import-truncated-shas' into 'master'

Fix bug that caused merge requests with diff notes imported from Bitbucket to raise errors

Closes #38100

See merge request gitlab-org/gitlab-ce!14438

3 files changed, 32 insertions, 10 deletions

diff --git a/lib/gitlab/bitbucket_import/importer.rb b/lib/gitlab/bitbucket_import/importer.rb
index 28bbf3b384e..d1979bb7ed3 100644
--- a/lib/gitlab/bitbucket_import/importer.rb
+++ b/lib/gitlab/bitbucket_import/importer.rb
@@ -149,16 +149,21 @@ module Gitlab
             description += @formatter.author_line(pull_request.author) unless find_user_id(pull_request.author)
             description += pull_request.description
 
+            source_branch_sha = pull_request.source_branch_sha
+            target_branch_sha = pull_request.target_branch_sha
+            source_branch_sha = project.repository.commit(source_branch_sha)&.sha || source_branch_sha
+            target_branch_sha = project.repository.commit(target_branch_sha)&.sha || target_branch_sha
+
             merge_request = project.merge_requests.create!(
               iid: pull_request.iid,
               title: pull_request.title,
               description: description,
               source_project: project,
               source_branch: pull_request.source_branch_name,
-              source_branch_sha: pull_request.source_branch_sha,
+              source_branch_sha: source_branch_sha,
               target_project: project,
               target_branch: pull_request.target_branch_name,
-              target_branch_sha: pull_request.target_branch_sha,
+              target_branch_sha: target_branch_sha,
               state: pull_request.state,
               author_id: gitlab_user_id(project, pull_request.author),
               assignee_id: nil,
diff --git a/lib/gitlab/diff/diff_refs.rb b/lib/gitlab/diff/diff_refs.rb
index 371cbe04b9b..c98eefbce25 100644
--- a/lib/gitlab/diff/diff_refs.rb
+++ b/lib/gitlab/diff/diff_refs.rb
@@ -13,9 +13,9 @@ module Gitlab
 
       def ==(other)
         other.is_a?(self.class) &&
-          base_sha == other.base_sha &&
-          start_sha == other.start_sha &&
-          head_sha == other.head_sha
+          shas_equal?(base_sha, other.base_sha) &&
+          shas_equal?(start_sha, other.start_sha) &&
+          shas_equal?(head_sha, other.head_sha)
       end
 
       alias_method :eql?, :==
@@ -47,6 +47,22 @@ module Gitlab
           CompareService.new(project, head_sha).execute(project, start_sha, straight: straight)
         end
       end
+
+      private
+
+      def shas_equal?(sha1, sha2)
+        return true if sha1 == sha2
+        return false if sha1.nil? || sha2.nil?
+        return false unless sha1.class == sha2.class
+
+        length = [sha1.length, sha2.length].min
+
+        # If either of the shas is below the minimum length, we cannot be sure
+        # that they actually refer to the same commit because of hash collision.
+        return false if length < Commit::MIN_SHA_LENGTH
+
+        sha1[0, length] == sha2[0, length]
+      end
     end
   end
 end
diff --git a/lib/gitlab/diff/position.rb b/lib/gitlab/diff/position.rb
index f80afb20f0c..b8db3adef0a 100644
--- a/lib/gitlab/diff/position.rb
+++ b/lib/gitlab/diff/position.rb
@@ -49,12 +49,13 @@ module Gitlab
         coder['attributes'] = self.to_h
       end
 
-      def key
-        @key ||= [base_sha, start_sha, head_sha, Digest::SHA1.hexdigest(old_path || ""), Digest::SHA1.hexdigest(new_path || ""), old_line, new_line]
-      end
-
       def ==(other)
-        other.is_a?(self.class) && key == other.key
+        other.is_a?(self.class) &&
+          other.diff_refs == diff_refs &&
+          other.old_path == old_path &&
+          other.new_path == new_path &&
+          other.old_line == old_line &&
+          other.new_line == new_line
       end
 
       def to_h