Ensure longer option is parsed with argument delimiters (#1179)

* Ensure longer option is parsed with argument delimiters

* PR feedback

Author: sfoslund

src/System.CommandLine.Tests/OptionTests.cs

@@ -371,12 +371,14 @@ public void When_Name_is_set_to_its_current_value_then_it_is_not_removed_from_al
             option.Aliases.Should().Contain("name");
         }
 
-        [Fact]
-        public void When_aliases_overlap_the_longer_alias_is_chosen()
+        [Theory]
+        [InlineData("-option value")]
+        [InlineData("-option:value")]
+        public void When_aliases_overlap_the_longer_alias_is_chosen(string parseInput)
         {
             var option = new Option<string>(new[] { "-o", "-option" });
 
-            var parseResult = option.Parse("-option value");
+            var parseResult = option.Parse(parseInput);
             parseResult.ValueForOption(option).Should().Be("value");
         }
 

src/System.CommandLine/Parsing/StringExtensions.cs

@@ -205,7 +205,10 @@ bool CanBeUnbundled(string arg, out IReadOnlyList<string>? replacement)
                 }
 
                 // don't unbundle if this is a known option
-                if (knownTokens.ContainsKey(arg))
+                if (knownTokens.ContainsKey(arg) ||
+                    knownTokens
+                        .SelectMany(token => _argumentDelimiters.Select(delimiter => token.Key + delimiter))
+                        .Any(token => arg.Contains(token)))
                 {
                     return false;
                 }