minor problems in git.c

Hi,

There are some minor problems in git.c:

(1) potential buffer overrun.

        strncat(&git_command[len], "/git-", sizeof(git_command) - len);
        len += 5;
        strncat(&git_command[len], argv[i], sizeof(git_command) - len);

The first line will write one byte ('\0') beyond the end of git_command, when sizeof(git_command) - len == 5.

The second line increase len by 5, without regarding how many bytes are written in the first line. It is possible to make len greater than sizeof(git_command), therefore make the third argument of the third line underflow, allowing almost any number of bytes from argv[1] to be copied.

(2) environ

int main(int argc, char **argv, char **envp)
{
  ...
  execve(git_command, &argv[i], envp);
  ...
}

I am wondering whether the global variable "environ" could change when you do setenv. Would it be clear by using the "environ" as the third argument of evecve()?

(3) printf("Failed to run command '%s': %s\n", git_command, strerror(errno)); should go to stderr?

Regards, Robertoo