  Automatic identification of the differences between two versions of a file is
a common and basic task in several applications of mining code repositories.
Git, a version control system, has a diff utility and users can select
algorithms of diff from the default algorithm Myers to the advanced Histogram
algorithm. From our systematic mapping, we identified three popular
applications of diff in recent studies. On the impact on code churn metrics in
14 Java projects, we obtained different values in 1.7% to 8.2% commits based on
the different diff algorithms. Regarding bug-introducing change identification,
we found 6.0% and 13.3% in the identified bug-fix commits had different results
of bug-introducing changes from 10 Java projects. For patch application, we
found that the Histogram is more suitable than Myers for providing the changes
of code, from our manual analysis. Thus, we strongly recommend using the
Histogram algorithm when mining Git repositories to consider differences in
source code.
