| Class | NoBugChangeFoundError | Raised when a BugChange class can't be found for an object. |
| Function | get_bug_change_class | Return a suitable IBugChange to describe obj and field_name. |
| Function | get_bug_changes | Generate IBugChange objects describing an IBugDelta. |
| Class | BugChangeBase | An abstract base class for Bug[Task]Changes. |
| Class | AttributeChange | A mixin class that provides basic functionality for `IBugChange`s. |
| Class | UnsubscribedFromBug | A user got unsubscribed from a bug. |
| Class | BugConvertedToQuestion | A bug got converted into a question. |
| Class | BugTaskAdded | A bug task got added to the bug. |
| Class | BugTaskDeleted | A bugtask was removed from the bug. |
| Class | SeriesNominated | A user nominated the bug to be fixed in a series. |
| Class | BugWatchAdded | A bug watch was added to the bug. |
| Class | BugWatchRemoved | A bug watch was removed from the bug. |
| Class | BranchLinkedToBug | A branch got linked to the bug. |
| Class | BranchUnlinkedFromBug | A branch got unlinked from the bug. |
| Class | MergeProposalLinkedToBug | A merge proposal got linked to the bug. |
| Class | MergeProposalUnlinkedFromBug | A merge proposal got unlinked from the bug. |
| Class | BugDescriptionChange | Describes a change to a bug's description. |
| Class | BugDuplicateChange | Describes a change to a bug's duplicate marker. |
| Class | BugTitleChange | Describes a change to a bug's title, aka summary. |
| Class | BugInformationTypeChange | Used to represent a change to the information_type of an IBug. |
| Class | BugTagsChange | Used to represent a change to an `IBug`s tags. |
| Function | download_url_of_bugattachment | Return the URL of the ProxiedLibraryFileAlias for the attachment. |
| Class | BugAttachmentChange | Used to represent a change to an IBug's attachments. |
| Class | CveLinkedToBug | Used to represent the linking of a CVE to a bug. |
| Class | CveUnlinkedFromBug | Used to represent the unlinking of a CVE from a bug. |
| Class | BugTaskAttributeChange | Used to represent a change in a BugTask's attributes. |
| Class | BugTaskImportanceChange | Represents a change in BugTask.importance. |
| Class | BugTaskStatusChange | Represents a change in BugTask.status. |
| Class | BugTaskMilestoneChange | Represents a change in BugTask.milestone. |
| Class | BugTaskBugWatchChange | Represents a change in BugTask.bugwatch. |
| Class | BugTaskAssigneeChange | Represents a change in BugTask.assignee. |
| Class | BugTaskTargetChange | Used to represent a change in a BugTask's target. |
| Function | _is_status_change_lifecycle_change | Is a status change a lifecycle change? |