[geary/wip/789271-broken-status: 1/3] Work around servers that send 0 as UIDVALIDITY values. Bug 789271.

[Michael Gratton <mjog src gnome org>]

commit e0fe86337be642425bc8d93651219c14e742e165
Author: Michael James Gratton <mike vee net>
Date:   Wed Oct 25 11:27:18 2017 +1100

    Work around servers that send 0 as UIDVALIDITY values. Bug 789271.

 src/engine/imap/message/imap-uid-validity.vala |   13 +++++++++----
 1 files changed, 9 insertions(+), 4 deletions(-)
---
diff --git a/src/engine/imap/message/imap-uid-validity.vala b/src/engine/imap/message/imap-uid-validity.vala
index 2f9ed82..ef63d1d 100644
--- a/src/engine/imap/message/imap-uid-validity.vala
+++ b/src/engine/imap/message/imap-uid-validity.vala
@@ -5,7 +5,7 @@
  */
 
 /*
- * A representation of IMAP's UIDVALIDITY.
+ * An IMAP unique identifier validity (UIDVALIDITY) value.
  *
  * See [[tools.ietf.org/html/rfc3501#section-2.3.1.1]]
  *
@@ -13,15 +13,20 @@
  */
 
 public class Geary.Imap.UIDValidity : Geary.MessageData.Int64MessageData, Geary.Imap.MessageData {
+
     /**
      * Minimum valid value for a {@link UIDValidity}.
+     *
+     * RFC 3501 defines UIDVALIDITY values as "nz-number", hence the
+     * minimum value here hshould be should be 1, however at least one
+     * server is sending 0. See Bug 789271.
      */
-    public const int64 MIN = 1;
-    
+    public const int64 MIN = 0;
+
     /**
      * Maximum valid value for a {@link UIDValidity}.
      *
-     * This is currently larger than what the spec allows for, since
+     * This is currently larger than what RFC 3501 allows for, since
      * at least one mail server was returning values greater than an
      * unsigned 32-bit integer. See Bug 755424.
      */