git-utils.sh: git_local_branch failes when using newer git

[Scott Little]

Brief Description
-----------------
git_local_branch is supposed to return the local branch name for a directory.
With newer versions of git, it sometimes gets confused and returning a tag name
instead.

Severity
--------
Minor

Steps to Reproduce
------------------
cd .repo/manifest
source git-utils.sh
git_local_branch $PWD

Expected Behavior
------------------
Returns the local branch name.
e.g. 'default' in the above scenario.

Actual Behavior
----------------
Sometimes it returns a tag instead, with a '~1' postfix.
I think git is now trying to say we are 'n' commits removed from the tag.
n=1 in this example.

This type of return value confuses the script that otherwise tries to filter out tags.

Reproducibility
---------------
Intermittent. Seems to depend on the version of git in use

System Configuration
--------------------
N/A

Branch/Pull Time/Commit
-----------------------
N/A

Last Pass
---------
N/A

Timestamp/Logs
--------------
N/A

Test Activity
-------------
Build

Workaround
----------
N/A

[Ghada Khalil (gkhalil)]

Marking as low severity as indicated by the reporter