GVFSVerb: check custom Git version bounds

We will use the following rules for testing the Git version is
compatible with the current version of VFS for Git:

1. The Platform must match ".vfs."

2. The version must be at least the fixed minimum revision.

3. The Revision must equal the current minimum revision.

This allows us to upgrade Git without updating VFS for Git. Thus, we
could reduce VFS for Git version upgrades when Git releases a security
update.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>

GVFS/GVFS/CommandLine/GVFSVerb.cs

@@ -884,27 +884,23 @@ private void CheckGitVersion(ITracer tracer, GVFSEnlistment enlistment, out stri
                 this.ReportErrorAndExit(tracer, "Error: Invalid version of git {0}.  Must use gvfs version.", version);
             }
 
-            if (ProcessHelper.IsDevelopmentVersion())
+            if (gitVersion.IsLessThan(GVFSConstants.SupportedGitVersion))
             {
-                if (gitVersion.IsLessThan(GVFSConstants.SupportedGitVersion))
-                {
-                    this.ReportErrorAndExit(
-                        tracer,
-                        "Error: Installed git version {0} is less than the supported version of {1}.",
-                        gitVersion,
-                        GVFSConstants.SupportedGitVersion);
-                }
+                this.ReportErrorAndExit(
+                    tracer,
+                    "Error: Installed git version {0} is less than the supported version of {1}.",
+                    gitVersion,
+                    GVFSConstants.SupportedGitVersion);
             }
-            else
+            else if (gitVersion.Revision != GVFSConstants.SupportedGitVersion.Revision)
             {
-                if (!gitVersion.IsEqualTo(GVFSConstants.SupportedGitVersion))
-                {
-                    this.ReportErrorAndExit(
-                        tracer,
-                        "Error: Installed git version {0} does not match supported version of {1}.",
-                        gitVersion,
-                        GVFSConstants.SupportedGitVersion);
-                }
+                this.ReportErrorAndExit(
+                    tracer,
+                    "Error: Installed git version {0} has revision number {1} instead of {2}." +
+                     " This Git version is too new, so either downgrade Git or upgrade VFS for Git",
+                    gitVersion,
+                    gitVersion.Revision,
+                    GVFSConstants.SupportedGitVersion.Revision);
             }
         }