Automatically apply "git update-index --chmod=+x" to executable files

Question

I frequently add bash scripts to my git repository, and the scripts have executable permissions in the linux filesystem prior to the git add. But after pushing the added files to a remote repository and pulling in another location, the files show up with non-executable permissions. There seem to be two ways to correct the problem:

1. chmod u+x $script 
   git commit -am "fixing the script permissions... again..."

or

2. git update-index --chmod=+x $script

Instead of fixing up the permissions every time, is there a way to have git simply look at the file permissions on the script during git add, recognize that "hey, this here is an executable file!" and add it to the repository with the exectuable permissions directly?

Answer 1

git 2.9.X/2.10 (Q3 2016) brings chmod to git add itself!

See commit 4e55ed3 (31 May 2016) by Edward Thomson (ethomson).
Helped-by: Johannes Schindelin (dscho).
^{(Merged by Junio C Hamano -- gitster -- in commit c8b080a, 06 Jul 2016)}

add: add --chmod=+x / --chmod=-x options

The executable bit will not be detected (and therefore will not be set) for paths in a repository with core.filemode set to false, though the users may still wish to add files as executable for compatibility with other users who do have core.filemode functionality.
For example, Windows users adding shell scripts may wish to add them as executable for compatibility with users on non-Windows.

Although this can be done with a plumbing command (git update-index --add --chmod=+x foo), teaching the git-add command allows users to set a file executable with a command that they're already familiar with.

You can see the origin of this new feature in "How to create file execute mode permissions in Git on Windows?" (Feb. 2011)