I was seeing the following occasionally in scripts:
> …/.pyenv/libexec/pyenv-version-file-read: line 12: type: write error: Broken pipe
This patch hopefully improves/fixes this, and it seems better anyway to
just use sed here.
With e.g. /usr/local/bin/.python-version owned by some user, `pyenv
local foo` would fail, if the user has no permissions for
`/usr/local/bin`, but only the `.python-version` file.
The `pwd` may return relative path if the `$PWD` is badly declared
in bash/zsh (e.g. `PWD="." bash`). To avoid the infinite loop in
`find_local_version_file()`, stop finding the version file if the
target paths are same consecutively.