объедините две или более историй развития вместе (Join two or more development histories together)
FAST-FORWARD MERGE
Often the current branch head is an ancestor of the named commit.
This is the most common case especially when invoked from git
pull: you are tracking an upstream repository, you have committed
no local changes, and now you want to update to a newer upstream
revision. In this case, a new commit is not needed to store the
combined history; instead, the HEAD (along with the index) is
updated to point at the named commit, without creating an extra
merge commit.
This behavior can be suppressed with the --no-ff option.
