clone: extract helper for checking mutually exclusive args

We have some duplicated code for aborting if the user provided
mutually exclusive arguments. Extensions surely have more such
code. We also have duplicated translations and inconsistent output in
this area.

This patch introduces a simpler helper for checking if more than one
option among a given set was given on the command line. I've made the
clone code call the function to show that it works.

The function has no good way of checking arguments with hyphens in
them. I'll add that later if necessary. The function still won't be
applicable in all cases, but I think it's still better than nothing.

Differential Revision: https://phab.mercurial-scm.org/D7633

mercurial/cmdutil.py

@@ -260,6 +260,18 b' debugrevlogopts = ['
 _linebelow = b"^HG: ------------------------ >8 ------------------------$"
 
 
+def check_at_most_one_arg(opts, *args):
+    """abort if more than one of the arguments are in opts"""
+    previous = None
+    for x in args:
+        if opts.get(x):
+            if previous:
+                raise error.Abort(
+                    _(b'cannot specify both --%s and --%s') % (previous, x)
+                )
+            previous = x
+
+
 def resolvecommitoptions(ui, opts):
     """modify commit options dict to handle related options
 

mercurial/commands.py

@@ -1889,8 +1889,7 b' def clone(ui, source, dest=None, **opts)'
     Returns 0 on success.
     """
     opts = pycompat.byteskwargs(opts)
-    if opts.get(b'noupdate') and opts.get(b'updaterev'):
-        raise error.Abort(_(b"cannot specify both --noupdate and --updaterev"))
+    cmdutil.check_at_most_one_arg(opts, b'noupdate', b'updaterev')
 
     # --include/--exclude can come from narrow or sparse.
     includepats, excludepats = None, None