Tags with names matching reports (like 'day') are not recorded

It seems to be impossible to track an interval with a tag that matches name of a report, like 'day', 'week', 'month', 'summary' or some initiall letters of the name of that report. The example output is

$ timew start 'summ' # or 's' or 'su' or 'sum' or 'summar' etc.
Tracking
Started 2018-06-07T13:49:18
Current 50:24
Total 0:01:06

If using with taskwarrior, this looks strange

$ task add pro:s +month +day +week 'summary'
Created task 708
$ task 708 start
Starting task d46a2aee 'summary'.
Tracking
Started 2018-06-07T13:53:49
Current 14:01:52
Total 0:08:47

I have timewarrior 1.1.1
python 2.7.15rc1
Linux 4.15.0-22-generic # 24-Ubuntu SMP Wed May 16 12:15:17 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux