try to fix for pyenv/virtualenv: completion/available/pip.completion.bash

completion/available/pip.completion.bash

@@ -5,6 +5,14 @@
 # If the pip package is installed within virtual environments, say, python managed by pyenv,
 # you should first initilization the corresponding environment.
 # So that the pip/pip3 is in system's path.
-if command -v pip >/dev/null; then
-  eval "$(pip completion --bash)"
+
+# For the pyenv-based environment:
+if which pyenv >/dev/null; then
+  if pyenv which pip 2>/dev/null; then
+    eval "$(pip completion --bash)"
+  fi
+else
+  if command -v pip >/dev/null; then
+    eval "$(pip completion --bash)"
+  fi
 fi