prepare_project_plot_data ValueError Exception

[monkut]

Error seems to occur when a project detail page tries to display the burndown chart when the project start date has not yet passed.

Internal Server Error: /prod/projects/
Traceback (most recent call last):
...
  File "/var/task/projects/views.py", line 110, in view_inprogress_projects_status
  script, div = prepare_burndown_chart_components(project)
  File "/var/task/projects/charts/functions.py", line 140, in prepare_burndown_chart_components
  data, assignees, burndown_line = prepare_project_plot_data(project, current_date)
  File "/var/task/projects/charts/functions.py", line 124, in prepare_project_plot_data
  unadded_dates = all_date_strings[all_date_strings.index(max_date_str) + 1:]
ValueError: '2018-09-28 (Fri)' is not in list