remove hg support from patchcheck (GH-7440)

(cherry picked from commit b8c0845)

Co-authored-by: Benjamin Peterson <benjamin@python.org>

Tools/scripts/patchcheck.py

@@ -44,16 +44,6 @@ def call_fxn(*args, **kwargs):
     return decorated_fxn
 
 
-def mq_patches_applied():
-    """Check if there are any applied MQ patches."""
-    cmd = 'hg qapplied'
-    with subprocess.Popen(cmd.split(),
-                          stdout=subprocess.PIPE,
-                          stderr=subprocess.PIPE) as st:
-        bstdout, _ = st.communicate()
-        return st.returncode == 0 and bstdout
-
-
 def get_git_branch():
     """Get the symbolic name for the current git branch"""
     cmd = "git rev-parse --abbrev-ref HEAD".split()
@@ -98,16 +88,8 @@ def get_base_branch():
 @status("Getting the list of files that have been added/changed",
         info=lambda x: n_files_str(len(x)))
 def changed_files(base_branch=None):
-    """Get the list of changed or added files from Mercurial or git."""
-    if os.path.isdir(os.path.join(SRCDIR, '.hg')):
-        if base_branch is not None:
-            sys.exit('need a git checkout to check PR status')
-        cmd = 'hg status --added --modified --no-status'
-        if mq_patches_applied():
-            cmd += ' --rev qparent'
-        with subprocess.Popen(cmd.split(), stdout=subprocess.PIPE) as st:
-            filenames = [x.decode().rstrip() for x in st.stdout]
-    elif os.path.exists(os.path.join(SRCDIR, '.git')):
+    """Get the list of changed or added files from git."""
+    if os.path.exists(os.path.join(SRCDIR, '.git')):
         # We just use an existence check here as:
         #  directory = normal git checkout/clone
         #  file = git worktree directory
@@ -129,7 +111,7 @@ def changed_files(base_branch=None):
                     filename = filename.split(' -> ', 2)[1].strip()
                 filenames.append(filename)
     else:
-        sys.exit('need a Mercurial or git checkout to get modified files')
+        sys.exit('need a git checkout to get modified files')
 
     filenames2 = []
     for filename in filenames: