Format codebase with black and check formatting in CQ

Apply rules set by https://gerrit-review.googlesource.com/c/git-repo/+/362954/ across the codebase and fix any lingering errors caught
by flake8. Also check black formatting in run_tests (and CQ).

Bug: b/267675342
Change-Id: I972d77649dac351150dcfeb1cd1ad0ea2efc1956
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/363474
Reviewed-by: Mike Frysinger <vapier@google.com>
Tested-by: Gavin Mak <gavinmak@google.com>
Commit-Queue: Gavin Mak <gavinmak@google.com>

pager.py

@@ -26,102 +26,101 @@ old_stderr = None
 
 
 def RunPager(globalConfig):
-  if not os.isatty(0) or not os.isatty(1):
-    return
-  pager = _SelectPager(globalConfig)
-  if pager == '' or pager == 'cat':
-    return
+    if not os.isatty(0) or not os.isatty(1):
+        return
+    pager = _SelectPager(globalConfig)
+    if pager == "" or pager == "cat":
+        return
 
-  if platform_utils.isWindows():
-    _PipePager(pager)
-  else:
-    _ForkPager(pager)
+    if platform_utils.isWindows():
+        _PipePager(pager)
+    else:
+        _ForkPager(pager)
 
 
 def TerminatePager():
-  global pager_process, old_stdout, old_stderr
-  if pager_process:
-    sys.stdout.flush()
-    sys.stderr.flush()
-    pager_process.stdin.close()
-    pager_process.wait()
-    pager_process = None
-    # Restore initial stdout/err in case there is more output in this process
-    # after shutting down the pager process
-    sys.stdout = old_stdout
-    sys.stderr = old_stderr
+    global pager_process, old_stdout, old_stderr
+    if pager_process:
+        sys.stdout.flush()
+        sys.stderr.flush()
+        pager_process.stdin.close()
+        pager_process.wait()
+        pager_process = None
+        # Restore initial stdout/err in case there is more output in this
+        # process after shutting down the pager process.
+        sys.stdout = old_stdout
+        sys.stderr = old_stderr
 
 
 def _PipePager(pager):
-  global pager_process, old_stdout, old_stderr
-  assert pager_process is None, "Only one active pager process at a time"
-  # Create pager process, piping stdout/err into its stdin
-  try:
-    pager_process = subprocess.Popen([pager], stdin=subprocess.PIPE, stdout=sys.stdout,
-                                     stderr=sys.stderr)
-  except FileNotFoundError:
-    sys.exit(f'fatal: cannot start pager "{pager}"')
-  old_stdout = sys.stdout
-  old_stderr = sys.stderr
-  sys.stdout = pager_process.stdin
-  sys.stderr = pager_process.stdin
+    global pager_process, old_stdout, old_stderr
+    assert pager_process is None, "Only one active pager process at a time"
+    # Create pager process, piping stdout/err into its stdin.
+    try:
+        pager_process = subprocess.Popen(
+            [pager], stdin=subprocess.PIPE, stdout=sys.stdout, stderr=sys.stderr
+        )
+    except FileNotFoundError:
+        sys.exit(f'fatal: cannot start pager "{pager}"')
+    old_stdout = sys.stdout
+    old_stderr = sys.stderr
+    sys.stdout = pager_process.stdin
+    sys.stderr = pager_process.stdin
 
 
 def _ForkPager(pager):
-  global active
-  # This process turns into the pager; a child it forks will
-  # do the real processing and output back to the pager. This
-  # is necessary to keep the pager in control of the tty.
-  #
-  try:
-    r, w = os.pipe()
-    pid = os.fork()
-    if not pid:
-      os.dup2(w, 1)
-      os.dup2(w, 2)
-      os.close(r)
-      os.close(w)
-      active = True
-      return
+    global active
+    # This process turns into the pager; a child it forks will
+    # do the real processing and output back to the pager. This
+    # is necessary to keep the pager in control of the tty.
+    try:
+        r, w = os.pipe()
+        pid = os.fork()
+        if not pid:
+            os.dup2(w, 1)
+            os.dup2(w, 2)
+            os.close(r)
+            os.close(w)
+            active = True
+            return
 
-    os.dup2(r, 0)
-    os.close(r)
-    os.close(w)
+        os.dup2(r, 0)
+        os.close(r)
+        os.close(w)
 
-    _BecomePager(pager)
-  except Exception:
-    print("fatal: cannot start pager '%s'" % pager, file=sys.stderr)
-    sys.exit(255)
+        _BecomePager(pager)
+    except Exception:
+        print("fatal: cannot start pager '%s'" % pager, file=sys.stderr)
+        sys.exit(255)
 
 
 def _SelectPager(globalConfig):
-  try:
-    return os.environ['GIT_PAGER']
-  except KeyError:
-    pass
+    try:
+        return os.environ["GIT_PAGER"]
+    except KeyError:
+        pass
 
-  pager = globalConfig.GetString('core.pager')
-  if pager:
-    return pager
+    pager = globalConfig.GetString("core.pager")
+    if pager:
+        return pager
 
-  try:
-    return os.environ['PAGER']
-  except KeyError:
-    pass
+    try:
+        return os.environ["PAGER"]
+    except KeyError:
+        pass
 
-  return 'less'
+    return "less"
 
 
 def _BecomePager(pager):
-  # Delaying execution of the pager until we have output
-  # ready works around a long-standing bug in popularly
-  # available versions of 'less', a better 'more'.
-  #
-  _a, _b, _c = select.select([0], [], [0])
+    # Delaying execution of the pager until we have output
+    # ready works around a long-standing bug in popularly
+    # available versions of 'less', a better 'more'.
+    _a, _b, _c = select.select([0], [], [0])
 
-  os.environ['LESS'] = 'FRSX'
+    os.environ["LESS"] = "FRSX"
 
-  try:
-    os.execvp(pager, [pager])
-  except OSError:
-    os.execv('/bin/sh', ['sh', '-c', pager])
+    try:
+        os.execvp(pager, [pager])
+    except OSError:
+        os.execv("/bin/sh", ["sh", "-c", pager])