recognise BitBucket hosts by WWW-Authenticate header

Tested with https://bitbucket.hl7.org

Author: hickford

src/shared/Atlassian.Bitbucket.Tests/BitbucketHostProviderTest.cs

@@ -55,6 +55,20 @@ public void BitbucketHostProvider_IsSupported(string protocol, string host, bool
             Assert.Equal(expected, provider.IsSupported(input));
         }
 
+        [Theory]
+        [InlineData("Basic realm=\"Atlassian Bitbucket\"", true)]
+        [InlineData("Basic realm=\"GitSponge\"", false)]
+        public void BitbucketHostProvider_IsSupported_WWWAuth(string wwwauth, bool expected)
+        {
+            var input = new InputArguments(new Dictionary<string, string>
+            {
+                ["wwwauth"] = wwwauth,
+            });
+
+            var provider = new BitbucketHostProvider(new TestCommandContext());
+            Assert.Equal(expected, provider.IsSupported(input));
+        }
+
         [Fact]
         public void BitbucketHostProvider_IsSupported_FailsForNullInput()
         {

src/shared/Atlassian.Bitbucket/BitbucketHostProvider.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Net.Http;
 using System.Threading.Tasks;
 using Atlassian.Bitbucket.Cloud;
@@ -43,6 +44,11 @@ public bool IsSupported(InputArguments input)
                 return false;
             }
 
+            if (input.WwwAuth.Any(x => x.Contains("realm=\"Atlassian Bitbucket\"", StringComparison.InvariantCultureIgnoreCase)))
+            {
+                return true;
+            }
+
             // Split port number and hostname from host input argument
             if (!input.TryGetHostAndPort(out string hostName, out _))
             {