Merge pull request #1719 from elebow/auto-pipenv-option-for-python-linters

Add python_[linter]_auto_pipenv options for python linters (fixes #1656)

autoload/ale/python.vim

@@ -1,6 +1,8 @@
 " Author: w0rp <devw0rp@gmail.com>
 " Description: Functions for integrating with Python linters.
 
+call ale#Set('python_auto_pipenv', '0')
+
 let s:sep = has('win32') ? '\' : '/'
 " bin is used for Unix virtualenv directories, and Scripts is for Windows.
 let s:bin_dir = has('unix') ? 'bin' : 'Scripts'
@@ -107,3 +109,8 @@ function! ale#python#FindExecutable(buffer, base_var_name, path_list) abort
 
     return ale#Var(a:buffer, a:base_var_name . '_executable')
 endfunction
+
+" Detects whether a pipenv environment is present.
+function! ale#python#PipenvPresent(buffer) abort
+    return findfile('Pipfile.lock', expand('#' . a:buffer . ':p:h') . ';') isnot# ''
+endfunction