ClearCase: checkins of different users may be grouped into the same changeset

In base ClearCase, the grouping of checkins into a changeset is done by taking the branch and the datetime (trimmed down to the minute) of the checking. This will result in incorrect grouping when:

• a user does multiple unrelated checkins on the same branch in the same minute.
• two users do unrelated checkins on the same branch in the same minute.