I have branch A. Head Revision is 1. Then, I create branch B from branch A with head revision 1. 

Afterwards, I am using branch B, until the head revision changed as below:

```
1
2
3
4
10 <- HEAD

```

Is there any Git Command I could run in branch B to get the revision number when 
the branch B first branch out? In this case, I want the command to return 1 as 1 is the head revision of branch A when branch B is created from branch A.

Thank you,

Hatjhie