fix: patch fix reload_doc

[gavindsouza]

Reload doc "Issue" in patch to fix missing attribute "options"

Traceback:

Executing erpnext.patches.v12_0.set_priority_for_support in test_something_del (_fdf332c084ad4987)
Traceback (most recent call last):
  File "/usr/local/Cellar/python/3.7.4/Frameworks/Python.framework/Versions/3.7/lib/python3.7/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/usr/local/Cellar/python/3.7.4/Frameworks/Python.framework/Versions/3.7/lib/python3.7/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/Users/gavin/Desktop/frappe-bench-dev/apps/frappe/frappe/utils/bench_helper.py", line 97, in <module>
    main()
  File "/Users/gavin/Desktop/frappe-bench-dev/apps/frappe/frappe/utils/bench_helper.py", line 18, in main
    click.Group(commands=commands)(prog_name='bench')
  File "/Users/gavin/Desktop/frappe-bench-dev/env/lib/python3.7/site-packages/click/core.py", line 764, in __call__
    return self.main(*args, **kwargs)
  File "/Users/gavin/Desktop/frappe-bench-dev/env/lib/python3.7/site-packages/click/core.py", line 717, in main
    rv = self.invoke(ctx)
  File "/Users/gavin/Desktop/frappe-bench-dev/env/lib/python3.7/site-packages/click/core.py", line 1137, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/Users/gavin/Desktop/frappe-bench-dev/env/lib/python3.7/site-packages/click/core.py", line 1137, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/Users/gavin/Desktop/frappe-bench-dev/env/lib/python3.7/site-packages/click/core.py", line 956, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/Users/gavin/Desktop/frappe-bench-dev/env/lib/python3.7/site-packages/click/core.py", line 555, in invoke
    return callback(*args, **kwargs)
  File "/Users/gavin/Desktop/frappe-bench-dev/env/lib/python3.7/site-packages/click/decorators.py", line 17, in new_func
    return f(get_current_context(), *args, **kwargs)
  File "/Users/gavin/Desktop/frappe-bench-dev/apps/frappe/frappe/commands/__init__.py", line 25, in _func
    ret = f(frappe._dict(ctx.obj), *args, **kwargs)
  File "/Users/gavin/Desktop/frappe-bench-dev/apps/frappe/frappe/commands/site.py", line 233, in migrate
    migrate(context.verbose, rebuild_website=rebuild_website, skip_failing=skip_failing)
  File "/Users/gavin/Desktop/frappe-bench-dev/apps/frappe/frappe/migrate.py", line 48, in migrate
    frappe.modules.patch_handler.run_all(skip_failing)
  File "/Users/gavin/Desktop/frappe-bench-dev/apps/frappe/frappe/modules/patch_handler.py", line 41, in run_all
    run_patch(patch)
  File "/Users/gavin/Desktop/frappe-bench-dev/apps/frappe/frappe/modules/patch_handler.py", line 30, in run_patch
    if not run_single(patchmodule = patch):
  File "/Users/gavin/Desktop/frappe-bench-dev/apps/frappe/frappe/modules/patch_handler.py", line 71, in run_single
    return execute_patch(patchmodule, method, methodargs)
  File "/Users/gavin/Desktop/frappe-bench-dev/apps/frappe/frappe/modules/patch_handler.py", line 91, in execute_patch
    frappe.get_attr(patchmodule.split()[0] + ".execute")()
  File "/Users/gavin/Desktop/frappe-bench-dev/apps/erpnext/erpnext/patches/v12_0/set_priority_for_support.py", line 7, in execute
    set_issue_priority()
  File "/Users/gavin/Desktop/frappe-bench-dev/apps/erpnext/erpnext/patches/v12_0/set_priority_for_support.py", line 14, in set_issue_priority
    for priority in frappe.get_meta("Issue").get_field("priority").options.split("\n"):
AttributeError: 'NoneType' object has no attribute 'options'