fix code style issues in easybuild.tools + add flake8 linting test

.github/workflows/linting.yml

@@ -0,0 +1,22 @@
+name: Static Analysis
+on: [push, pull_request]
+jobs:
+  python-linting:
+    runs-on: ubuntu-18.04
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: set up Python
+      uses: actions/setup-python@v1
+      with:
+        python-version: 3.8
+
+    - name: install Python packages
+      run: |
+        pip install --upgrade pip
+        pip install --upgrade flake8
+
+    - name: Run flake8
+      run: |
+        flake8 easybuild/tools
+

easybuild/tools/asyncprocess.py

@@ -66,16 +66,15 @@
 """
 
 import errno
+import fcntl
 import os
+import select
 import subprocess
 import time
 
 PIPE = subprocess.PIPE
 STDOUT = subprocess.STDOUT
 
-import select  #@UnresolvedImport
-import fcntl  #@UnresolvedImport
-
 
 class Popen(subprocess.Popen):
 
@@ -117,7 +116,7 @@ def send(self, inp):
         try:
             written = os.write(self.stdin.fileno(), inp.encode())
         except OSError as why:
-            if why[0] == errno.EPIPE: #broken pipe
+            if why[0] == errno.EPIPE:  # broken pipe
                 return self._close('stdin')
             raise
 
@@ -147,8 +146,10 @@ def _recv(self, which, maxsize):
             if not conn.closed:
                 fcntl.fcntl(conn, fcntl.F_SETFL, flags)
 
+
 message = "Other end disconnected!"
 
+
 def recv_some(p, t=.2, e=1, tr=5, stderr=0):
     if tr < 1:
         tr = 1
@@ -171,6 +172,7 @@ def recv_some(p, t=.2, e=1, tr=5, stderr=0):
             time.sleep(max((x - time.time()) / tr, 0))
     return b''.join(y)
 
+
 def send_all(p, data):
     while len(data):
         sent = p.send(data)