--output relative to the project directory even when running from another directory #77
Description
Poetry can be run from within a sub directory, hence the command poetry export --output foo/requirements.txt can misleading:
$ ls
my_project
pyproject.toml
$ mkdir tmp && pushd tmp # Go in a sub directory
$ mkdir foo
$ poetry export --output foo/requirements.txt # User expects to write into C:\\Users\\gbleu\\my_project\\tmp\\foo\\requirements.txt
[Errno 2] No such file or directory: 'C:\\Users\\gbleu\\my_project\\foo\\requirements.txt'
$ poetry export --output requirements.txt # User expects to write into C:\\Users\\gbleu\\my_project\\tmp\\requirements.txt
$ ls
$ ls .. # export have been actually written into C:\\Users\\gbleu\\my_project\\requirements.txt
my_project
pyproject.toml
requirements.txt