[myself@somehost ~]$ mkdir bubu
[myself@somehost ~]$ cd bubu
[myself@somehost bubu]$ git init
Initialized empty Git repository in /home/myself/bubu/.git/
[myself@somehost bubu]$ cat > file


[myself@somehost bubu]$ git add file
[myself@somehost bubu]$ git commit
[master (root-commit) 30b5b60] first
 1 files changed, 2 insertions(+), 0 deletions(-)
 create mode 100644 file
[myself@somehost bubu]$ git checkout -b branch1
Switched to a new branch 'branch1'
[myself@somehost bubu]$ emacs file
[myself@somehost bubu]$ # added a in first line
[myself@somehost bubu]$ git commit -a -m 'added a in first line'
[branch1 4ac5e60] added a in first line
 1 files changed, 1 insertions(+), 1 deletions(-)
[myself@somehost bubu]$ git checkout 30b5b60
Note: checking out '30b5b60'.

You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by performing another checkout.

If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -b with the checkout command again. Example:

  git checkout -b new_branch_name

HEAD is now at 30b5b60... first
[myself@somehost bubu]$ git checkout -b branch2
Switched to a new branch 'branch2'
[myself@somehost bubu]$ emacs file
[myself@somehost bubu]$ git commit -a -m 'added b in second line'
[branch2 d6817e7] added b in second line
 1 files changed, 1 insertions(+), 1 deletions(-)
[myself@somehost bubu]$ git merge branch1
Auto-merging file
CONFLICT (content): Merge conflict in file
Automatic merge failed; fix conflicts and then commit the result.
[myself@somehost bubu]$ emacs file
[myself@somehost bubu]$ # I resolved the conflict wrong on purpose
[myself@somehost bubu]$ git commit -a # On purpose I get rid of the message
[branch2 7b57499] merge with hidden conflicts
[myself@somehost bubu]$ gitk
[myself@somehost bubu]$ #gitk did not show the manually resolved conflict