Re: [PATCH] sequencer: pass absolute GIT_DIR to exec commands

> From: Jacob Keller <jacob.keller@gmail.com>
> 
> When we replaced the old shell script based interactive rebase in
> commmit 18633e1a22a6 ("rebase -i: use the rebase--helper builtin",
> 2017-02-09) we introduced a regression of functionality in that the
> GIT_DIR would be sent to the environment of the exec command as-is.
> 
> This generally meant that it would be passed as "GIT_DIR=.git", which
> causes problems for any exec command that wants to run git commands in
> a subdirectory.
> 
> This isn't a very large regression, since it is not that likely that the
> exec command will run a git command, and even less likely that it will
> need to do so in a subdir. This regression was discovered by a build
> system which uses git-describe to find the current version of the build
> system, and happened to do so from the src/ sub directory of the
> project.
> 
> Fix this by passing in the absolute path of the git directory into the
> child environment.
> 
> Signed-off-by: Jacob Keller <jacob.keller@gmail.com>