Re: [PATCH v5] lockfile.c: store absolute path

> Locked paths can be saved in a linked list so that if something wrong
> happens, *.lock are removed. For relative paths, this works fine if we
> keep cwd the same, which is true 99% of time except:
> 
> - update-index and read-tree hold the lock on $GIT_DIR/index really
>   early, then later on may call setup_work_tree() to move cwd.
> 
> - Suppose a lock is being held (e.g. by "git add") then somewhere
>   down the line, somebody calls real_path (e.g. "link_alt_odb_entry"),
>   which temporarily moves cwd away and back.
> 
> During that time when cwd is moved (either permanently or temporarily)
> and we decide to die(), attempts to remove relative *.lock will fail,
> and the next operation will complain that some files are still locked.
> 
> Avoid this case by turning relative paths to absolute before storing
> the path in "filename" field.