plugins/sources/pip.py: also look for python version named "python"
In some virtual environments, we might not have the binary with the
exact python version, which would lead the current pip plugin to
fail to find a working pip version.
This adds "python" at the start of the list of valid python versions
diff --git a/buildstream/plugins/sources/pip.py b/buildstream/plugins/sources/pip.py
index 2ef4016..df2eeb5 100644
--- a/buildstream/plugins/sources/pip.py
+++ b/buildstream/plugins/sources/pip.py
@@ -80,6 +80,7 @@
# Used only for finding pip command
_PYTHON_VERSIONS = [
+ 'python', # when running in a venv, we might not have the exact version
'python2.7',
'python3.0',
'python3.1',
