Encoding to .m4v container with HEVC issue

[Atarikid]

With FFmpeg 4.1 up to the latest daily build of 16/1/2019 FFmpeg throws an error when you try to encode to a .m4v container with HEVC video codec.
The error log tells me HEVC isn't supported for .m4v

This is a regression issue because it did work with FFmpeg 4.0.2

Here is the full uncut ffmpeg log:

macpro:~ testsystem$ /Users/testsystem/Library/Application\ Support/FFmpegTools/ffmpeg -i /Users/testsystem/Desktop/Royale.mov -c:v libx265 -y /Users/testsystem/Movies/Royale.m4v
ffmpeg version N-92966-gd52a1be4e3-tessus ​https://evermeet.cx/ffmpeg/ Copyright (c) 2000-2019 the FFmpeg developers

built with Apple LLVM version 10.0.0 (clang-1000.11.45.5)
configuration: --cc=/usr/bin/clang --prefix=/opt/ffmpeg --extra-version=tessus --enable-avisynth --enable-fontconfig --enable-gpl --enable-libaom --enable-libass --enable-libbluray --enable-libdav1d --enable-libfreetype --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libmysofa --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopus --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-libzmq --enable-libzvbi --enable-version3 --pkg-config-flags=--static --disable-ffplay
libavutil 56. 25.100 / 56. 25.100
libavcodec 58. 43.101 / 58. 43.101
libavformat 58. 25.100 / 58. 25.100
libavdevice 58. 6.101 / 58. 6.101
libavfilter 7. 48.100 / 7. 48.100
libswscale 5. 4.100 / 5. 4.100
libswresample 3. 4.100 / 3. 4.100
libpostproc 55. 4.100 / 55. 4.100

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/Users/testsystem/Desktop/Royale.mov':

Metadata:

major_brand : qt
minor_version : 512
compatible_brands: qt
creation_time : 2018-12-30T19:02:30.000000Z
encoder : Lavf58.23.101

Duration: 00:02:34.58, start: 0.000000, bitrate: 1607 kb/s

Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1024x426 [SAR 1:1 DAR 512:213], 1605 kb/s, SAR 26625:26624 DAR 125:52, 24.99 fps, 24.99 tbr, 19992 tbn, 49.98 tbc (default)
Metadata:

creation_time : 2018-12-30T19:02:30.000000Z
handler_name : VideoHandler
encoder : Lavc58.40.100 libx264

Stream mapping:

Stream #0:0 -> #0:0 (h264 (native) -> hevc (libx265))

Press [q] to stop, ? for help
x265 [info]: HEVC encoder version 3.0_RC+10-672ce0547e97
x265 [info]: build info [Mac OS X][clang 10.0.0][64 bit] 8bit+10bit+12bit
x265 [info]: using cpu capabilities: MMX2 SSE2Fast LZCNT SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
x265 [info]: Main profile, Level-3 (Main tier)
x265 [info]: Thread pool created using 12 threads
x265 [info]: Slices : 1
x265 [info]: frame threads / pool features : 3 / wpp(7 rows)
x265 [warning]: Source height < 720p; disabling lookahead-slices
x265 [info]: Coding QT: max CU size, min CU size : 64 / 8
x265 [info]: Residual QT: max TU size, max depth : 32 / 1 inter / 1 intra
x265 [info]: ME / range / subpel / merge : hex / 57 / 2 / 2
x265 [info]: Keyframe min / max / scenecut / bias: 24 / 250 / 40 / 5.00
x265 [info]: Lookahead / bframes / badapt : 20 / 4 / 2
x265 [info]: b-pyramid / weightp / weightb : 1 / 1 / 0
x265 [info]: References / ref-limit cu / depth : 3 / on / on
x265 [info]: AQ: mode / str / qg-size / cu-tree : 2 / 1.0 / 32 / 1
x265 [info]: Rate Control / qCompress : CRF-28.0 / 0.60
x265 [info]: tools: rd=3 psy-rd=2.00 rskip signhide tmvp strong-intra-smoothing
x265 [info]: tools: deblock sao
[ipod @ 0x7fbed081ca00] Could not find tag for codec hevc in stream #0, codec not currently supported in container
Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument
Error initializing output stream 0:0 --

encoded 0 frames
Conversion failed!

[Carl Eugen Hoyos]

This was a bug, use -f mp4 or -f mov if you want to use HEVC to avoid writing invalid files.