Mostly-null merge from 3.4. (Only added the tag for 3.4.4rc1.)

diff --cc .hgtags
index 8d5f662afdfd28158b03cfc6c08d655012d9561b,0026e8dff8baa3adbbf8ad90d72c83798b93379f..e2a9eb071594825b01911ee6f743858f9cba3785
--- 1/.hgtags
--- 2/.hgtags
+++ b/.hgtags
@@@ -144,18 -144,4 +144,19 @@@ c0e311e010fcb5bae8d87ca22051cd0845ea0ca
  ab2c023a9432f16652e89c404bbc84aa91bf55af v3.4.2
  69dd528ca6255a66c37cc5cf680e8357d108b036 v3.4.3rc1
  b4cbecbc0781e89a309d03b60a1f75f8499250e6 v3.4.3
+ 04f3f725896c6961212c3a12e8ac25be6958f4fa v3.4.4rc1
 +5d4b6a57d5fd7564bf73f3db0e46fe5eeb00bcd8 v3.5.0a1
 +0337bd7ebcb6559d69679bc7025059ad1ce4f432 v3.5.0a2
 +82656e28b5e5c4ae48d8dd8b5f0d7968908a82b6 v3.5.0a3
 +413e0e0004f4f954331cb8122aa55fe208984955 v3.5.0a4
 +071fefbb5e3db770c6c19fba9994699f121b1cea v3.5.0b1
 +7a088af5615bf04024e9912068f4bd8f43ed3917 v3.5.0b2
 +0035fcd9b9243ae52c2e830204fd9c1f7d528534 v3.5.0b3
 +c0d64105463581f85d0e368e8d6e59b7fd8f12b1 v3.5.0b4
 +1a58b1227501e046eee13d90f113417b60843301 v3.5.0rc1
 +cc15d736d860303b9da90d43cd32db39bab048df v3.5.0rc2
 +66ed52375df802f9d0a34480daaa8ce79fc41313 v3.5.0rc3
 +2d033fedfa7f1e325fd14ccdaa9cb42155da206f v3.5.0rc4
 +374f501f4567b7595f2ad7798aa09afa2456bb28 v3.5.0
 +948ef16a69513ba1ff15c9d7d0b012b949df4c80 v3.5.1rc1
 +37a07cee5969e6d3672583187a73cf636ff28e1b v3.5.1