[geary] Don't merge emails if they do not share the same Message-ID. Bug 713530

[Michael Gratton <mjog src gnome org>]

commit d33febbc056ea90330485cd8d0b4bb7dd08baabe
Author: Gautier Pelloux-Prayer <gautier+git damsy net>
Date:   Thu Dec 29 16:44:16 2016 +0100

    Don't merge emails if they do not share the same Message-ID. Bug 713530
    
    In some cases, it may happen that a mail is being sent multiple times simultaneously
    to the same recipient.
    The only modified field being the Message-ID, we have to check it as well as
    message's size before merging 2 mails together.
    Otherwise, at each start-up Geary will try to fetch "missing mails" but will never
    succeed to do so.

 src/engine/imap-db/imap-db-folder.vala             |   14 ++++++++++----
 .../imap-engine-account-synchronizer.vala          |   11 ++++++-----
 2 files changed, 16 insertions(+), 9 deletions(-)
---
diff --git a/src/engine/imap-db/imap-db-folder.vala b/src/engine/imap-db/imap-db-folder.vala
index 66f9726..18d0123 100644
--- a/src/engine/imap-db/imap-db-folder.vala
+++ b/src/engine/imap-db/imap-db-folder.vala
@@ -1234,13 +1234,19 @@ private class Geary.ImapDB.Folder : BaseObject, Geary.ReferenceSemantics {
             
             return null;
         }
-        
+
         // look for duplicate in IMAP message properties
-        Db.Statement stmt = cx.prepare(
-            "SELECT id FROM MessageTable WHERE internaldate=? AND rfc822_size=?");
+        Db.Statement stmt;
+        if (email.message_id != null)
+            stmt = cx.prepare("SELECT id FROM MessageTable WHERE internaldate=? AND rfc822_size=? AND 
message_id=?");
+         else
+            stmt = cx.prepare("SELECT id FROM MessageTable WHERE internaldate=? AND rfc822_size=?");
+
         stmt.bind_string(0, internaldate);
         stmt.bind_int64(1, rfc822_size);
-        
+        if (email.message_id != null)
+            stmt.bind_string(2, email.message_id.to_string());
+
         Db.Result results = stmt.exec(cancellable);
         // no duplicates found
         if (results.finished)
diff --git a/src/engine/imap-engine/imap-engine-account-synchronizer.vala 
b/src/engine/imap-engine/imap-engine-account-synchronizer.vala
index a41c72f..f2899e3 100644
--- a/src/engine/imap-engine/imap-engine-account-synchronizer.vala
+++ b/src/engine/imap-engine/imap-engine-account-synchronizer.vala
@@ -398,17 +398,18 @@ private class Geary.ImapEngine.AccountSynchronizer : Geary.BaseObject {
                 
                 // if past max_epoch, then just pull in everything and be done with it
                 if (current_epoch.compare(max_epoch) < 0) {
-                    debug("Background sync reached max epoch of %s, fetching all mail from %s",
-                        max_epoch.to_string(), folder.to_string());
-                    
+                    debug("Background sync reached max epoch of %s, fetching all mail from %s (already got 
%d of %d emails)",
+                        max_epoch.to_string(), folder.to_string(), local_count, 
folder.properties.email_total);
+
                     yield folder.list_email_by_id_async(null, 1, Geary.Email.Field.NONE,
                         Geary.Folder.ListFlags.OLDEST_TO_NEWEST, bg_cancellable);
                 } else {
                     // don't go past proscribed epoch
                     if (current_epoch.compare(epoch) < 0)
                         current_epoch = epoch;
-                    
-                    debug("Background sync'ing %s to %s", folder.to_string(), current_epoch.to_string());
+
+                    debug("Background sync'ing %s to %s (already got %d of %d emails)",
+                        folder.to_string(), current_epoch.to_string(), local_count, 
folder.properties.email_total);
                     Geary.EmailIdentifier? earliest_span_id = yield 
folder.find_earliest_email_async(current_epoch,
                         oldest_local_id, bg_cancellable);
                     if (earliest_span_id == null && current_epoch.compare(epoch) <= 0) {