[depot tools] Remove `git cl issue --switch`

This was a duplicate of `git cl checkout`

Revert "[depot tools] Add `git cl issue --switch`"
Revert "[depot_tools] Use a function instead of reimplementing it."

This reverts commits 61ebd177abdc56bd373fc05c0101e2e506f9d758 and
7f9b0231c460eae158c3d2fd231345ed6588f8dc.

Bug: 1428476
Change-Id: I54b70d7c7e98c847768cd980b337510fb91cdb20
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/4405816
Reviewed-by: Gavin Mak <gavinmak@google.com>
Commit-Queue: Arthur Milchior <arthurmilchior@chromium.org>

git_cl.py

@@ -4218,105 +4218,53 @@ def write_json(path, contents):
       json.dump(contents, f)
 
 
-def _GetIssueBranchMap():
-  # type: () -> Dict[int, List]
-  """Associate issues (as number) to the list of branches associated to this
-  issue."""
-  branches = RunGit(['for-each-ref', 'refs/heads',
-                     '--format=%(refname)']).splitlines()
-  # Reverse issue lookup.
-  issue_branch_map = {}
-
-  git_config = {}
-  for config in RunGit(['config', '--get-regexp',
-                        r'branch\..*issue']).splitlines():
-    name, _space, val = config.partition(' ')
-    git_config[name] = val
-
-  for branch in branches:
-    issue = git_config.get('branch.%s.%s' %
-                           (scm.GIT.ShortBranchName(branch), ISSUE_CONFIG_KEY))
-    if issue:
-      issue_branch_map.setdefault(int(issue), []).append(branch)
-  return issue_branch_map
-
-
-def SwitchToIssue(options, args):
-  """Switch to the branch associated to issue args[0]
-
-  Fail if the first arg is not a number. Fail if there are 0 such branch.
-  If there are multiple such branch, warns and behaves as
-  `git cl issue -r issue_number`.
-  """
-  issue_branch_map = _GetIssueBranchMap()
-  if not args:
-    DieWithError('`git cl issue --switch` requires a number.')
-  try:
-    issue_num = int(args[0])
-  except ValueError:
-    DieWithError('Cannot parse issue number: %s' % args[0])
-  branches = issue_branch_map.get(issue_num, [])
-  if not branches:
-    DieWithError('No branch associated to issue: %d' % issue_num)
-  if len(branches) > 1:
-    # Print the various branches
-    PrintIssueToBranches(options, args)
-    DieWithError('Multiple branches associated to issue: %d' % issue_num)
-  RunGit(['switch', scm.GIT.ShortBranchName(branches[0])])
-  return 0
-
-
-def PrintIssueToBranches(options, args):
-  """Print the name of the branch(es) associated to the issue.
-
-  If no issue is specified, print issue -> branch(es) for all known issues"""
-  # Reverse issue lookup.
-  issue_branch_map = _GetIssueBranchMap()
-
-  if not args:
-    args = sorted(issue_branch_map.keys())
-  result = {}
-  for issue in args:
-    try:
-      issue_num = int(issue)
-    except ValueError:
-      print('ERROR cannot parse issue number: %s' % issue, file=sys.stderr)
-      continue
-    result[issue_num] = issue_branch_map.get(issue_num)
-    print('Branch for issue number %s: %s' %
-          (issue, ', '.join(issue_branch_map.get(issue_num) or ('None', ))))
-  if options.json:
-    write_json(options.json, result)
-  return 0
-
-
 @subcommand.usage('[issue_number]')
 @metrics.collector.collect_metrics('git cl issue')
 def CMDissue(parser, args):
   """Sets or displays the current code review issue number.
 
   Pass issue number 0 to clear the current issue.
-  --reverse and --switch option allow to access branch(es) from issue number.
   """
   parser.add_option('-r', '--reverse', action='store_true',
                     help='Lookup the branch(es) for the specified issues. If '
                          'no issues are specified, all branches with mapped '
                          'issues will be listed.')
-  parser.add_option('-s',
-                    '--switch',
-                    action='store_true',
-                    help='Switch to the branch linked to the specified issue. '
-                    'If multiple branches are linked, list all of them.'
-                    'Fail if `git switch` would fail in current state.')
   parser.add_option('--json',
                     help='Path to JSON output file, or "-" for stdout.')
   options, args = parser.parse_args(args)
 
-  if options.switch:
-    return SwitchToIssue(options, args)
-
   if options.reverse:
-    return PrintIssueToBranches(options, args)
+    branches = RunGit(['for-each-ref', 'refs/heads',
+                       '--format=%(refname)']).splitlines()
+    # Reverse issue lookup.
+    issue_branch_map = {}
+
+    git_config = {}
+    for config in RunGit(['config', '--get-regexp',
+                          r'branch\..*issue']).splitlines():
+      name, _space, val = config.partition(' ')
+      git_config[name] = val
+
+    for branch in branches:
+      issue = git_config.get(
+          'branch.%s.%s' % (scm.GIT.ShortBranchName(branch), ISSUE_CONFIG_KEY))
+      if issue:
+        issue_branch_map.setdefault(int(issue), []).append(branch)
+    if not args:
+      args = sorted(issue_branch_map.keys())
+    result = {}
+    for issue in args:
+      try:
+        issue_num = int(issue)
+      except ValueError:
+        print('ERROR cannot parse issue number: %s' % issue, file=sys.stderr)
+        continue
+      result[issue_num] = issue_branch_map.get(issue_num)
+      print('Branch for issue number %s: %s' %
+            (issue, ', '.join(issue_branch_map.get(issue_num) or ('None', ))))
+    if options.json:
+      write_json(options.json, result)
+    return 0
 
   if len(args) > 0:
     issue = ParseIssueNumberArgument(args[0])