setup: don't die if realpath(3) fails on getcwd(3)

Prior to Git 2.35.0, git could be run from an inaccessible working directory so long as the git repository specified by options and/or environment variables was accessible. For example: git init repo mkdir -p a/b cd a/b chmod u-x .. git -C "${PWD%/a/b}/repo" status If this example seems a bit contrived, consider running with the repository owner as a substitute UID (e.g. with runuser(1) or sudo(8)) without ensuring the working directory is accessible by that user. The code added by e6f8861bd4 ("setup: introduce startup_info->original_cwd") to preserve the working directory attempts to normalize the path using strbuf_realpath(). If that fails, as in the case above, it is treated as a fatal error. This commit treats strbuf_realpath() errors as non-fatal. If an error occurs, setup_original_cwd() will continue without applying removal prevention for cwd, resulting in the pre-2.35.0 behavior. The risk should be minimal, since git will not operate on a repository with inaccessible ancestors, this behavior is only known to occur when cwd is a descendant of the repository, an ancestor of cwd is inaccessible, and no ancestors of the repository are inaccessible. Signed-off-by: Kevin Locke <kevin@kevinlocke.name> Reviewed-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>