gitk: Allow forcing branch creation if it already exists
gitk: Allow forcing branch creation if it already exists

If gitk knows that the branch the user tries to create exists,
it should ask whether it should overwrite it.  This way the user
can either decide to choose a new name, or move the head while
preserving the reflog.

Signed-off-by: Alexander Gavrilov <75c96f70141fec65a655d202cd4821a09cb99fd1@gmail.com>
Signed-off-by: Paul Mackerras <19a0ba370c443ba08d20b5061586430ab449ee8c@samba.org>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git