baseparse: Always clear drain flag before pulling

In pull mode, each pull is unique. A following pull can be well inside the
range even if the previous one wasn't. Fix this my moving the drain flag
right before the pull.

This avoids passing a bad drain flag to parsers, which may endup truncate
buffers causing data corruption.

Fixes gstreamer/gst-plugins-bad#1275

Part-of: <gstreamer/gstreamer!446>
65 jobs for !446 with baseparse-clear-drain-flag in 72 minutes and 24 seconds (queued for 4 seconds)
detached
Status Job ID Name Coverage
  Preparation
passed #2408295
gst indent

00:00:31

passed #2408293
manifest

00:00:59

 
  Build
passed #2408311
gstreamer
build cerbero cross-android universal

00:06:21

passed #2411630
gst-ios-13.2
build cerbero cross-ios universal

00:17:54

passed #2408313
gstreamer
build cerbero cross win32

00:07:18

passed #2408315
gstreamer
build cerbero cross win64

00:04:52

passed #2408309
gstreamer
build cerbero fedora x86_64

00:03:52

passed #2411629
gst-macos-10.15
build cerbero macos x86_64

00:09:08

passed #2409083
build clang fedora x86_64

00:05:23

passed #2412590
docker windows 1809
build msys2

00:25:25

passed #2408296
build nodebug fedora x86_64

00:06:03

passed #2408298
build static fedora x86_64

00:04:31

passed #2408299
build static nodebug fedora x86_64

00:06:04

passed #2412591
docker windows 1809
build vs2017 amd64

00:11:11

passed #2411625
docker windows 1809
build vs2017 x86

00:09:54

failed #2409088
gst-ios-13.2
build cerbero cross-ios universal

00:00:55

failed #2409221
gst-ios-13.2
build cerbero cross-ios universal

00:01:06

failed #2408319
gst-ios-13.2
build cerbero cross-ios universal

00:04:33

failed #2409153
gst-ios-13.2
build cerbero cross-ios universal

00:01:00

failed #2409101
gst-ios-13.2
build cerbero cross-ios universal

00:00:59

failed #2409102
gst-macos-10.15
build cerbero macos x86_64

00:00:59

failed #2409087
gst-macos-10.15
build cerbero macos x86_64

00:00:52

failed #2409220
gst-macos-10.15
build cerbero macos x86_64

00:01:12

failed #2409154
gst-macos-10.15
build cerbero macos x86_64

00:01:00

failed #2408317
gst-macos-10.15
build cerbero macos x86_64

00:02:33

failed #2408301
build clang fedora x86_64

00:01:07

failed #2408307
docker windows 1809
build msys2

00:05:49

failed #2409224
docker windows 1809
build msys2

02:03:11

failed #2409086
docker windows 1809
build msys2

00:06:55

failed #2411631
docker windows 1809
build vs2017 amd64

00:45:01

failed #2409084
docker windows 1809
build vs2017 amd64

00:04:27

failed #2408303
docker windows 1809
build vs2017 amd64

00:03:11

failed #2409225
docker windows 1809
build vs2017 amd64

00:45:01

failed #2409085
docker windows 1809
build vs2017 x86

00:45:01

failed #2408305
docker windows 1809
build vs2017 x86

00:03:42

 
  Test
passed #2409089
gstreamer
check fedora

00:07:05

passed #2411626
gstreamer
integration testsuites fedora 1/4

00:17:51

passed #2411627
gstreamer
integration testsuites fedora 2/4

00:16:37

passed #2409092
gstreamer
integration testsuites fedora 3/4

00:14:45

passed #2409093
gstreamer
integration testsuites fedora 4/4

00:14:40

passed #2409098
gstreamer
valgrind bad

00:07:16

passed #2409095
gstreamer
valgrind base

00:09:07

passed #2409094
gstreamer
valgrind core

00:11:22

passed #2411628
gstreamer
valgrind ges

00:07:42

passed #2409096
gstreamer
valgrind good

00:13:19

passed #2409219
gstreamer
valgrind ugly

00:05:17

failed #2408321
gstreamer
check fedora

00:03:15

failed #2408323
gstreamer
integration testsuites fedora 1/4

00:03:14

failed #2409090
gstreamer
integration testsuites fedora 1/4

00:01:09

failed #2408325
gstreamer
integration testsuites fedora 2/4

00:03:09

failed #2409091
gstreamer
integration testsuites fedora 2/4

00:01:06

failed #2408327
gstreamer
integration testsuites fedora 3/4

00:03:09

failed #2408329
gstreamer
integration testsuites fedora 4/4

00:03:13

failed #2408337
gstreamer
valgrind bad

00:01:01

failed #2408334
gstreamer
valgrind base

00:01:04

failed #2408331
gstreamer
valgrind core

00:00:58

failed #2409099
gstreamer
valgrind ges

00:19:01

failed #2408338
gstreamer
valgrind ges

00:01:16

failed #2408335
gstreamer
valgrind good

00:01:53

failed #2408336
gstreamer
valgrind ugly

00:01:05

failed #2409097
gstreamer
valgrind ugly

00:01:04

 
  Integrate
passed #2408339
cross-android universal examples

00:03:10

passed #2408341
gst-ios-13.2
cross-ios universal examples

00:03:36

passed #2409100
documentation

00:08:46

failed #2408340
documentation

00:02:22