libopencv-dev pkgconfig include path info is wrong (missing suffix "2")

[Marc Olzheim]

marcolz:/>cat /usr/lib/pkgconfig/opencv.pc
# Package Information for pkg-config

prefix=/usr
exec_prefix=${prefix}
libdir=${exec_prefix}/lib
includedir_old=${prefix}/include/opencv
includedir_new=${prefix}/include

Name: OpenCV
Description: Open Source Computer Vision Library
Version: 2.3.1
Libs: -L${libdir} -lopencv_core -lopencv_imgproc -lopencv_highgui -lopencv_ml -lopencv_video -lopencv_features2d -lopencv_calib3d -lopencv_objdetect -lopencv_contrib -lopencv_legacy -lopencv_flann
Cflags: -I${includedir_old} -I${includedir_new}
marcolz:/>ls -lad /usr/include/opencv*
drwxr-xr-x 14 root root 4096 Jun 27 10:55 /usr/include/opencv2
marcolz:/>dpkg -S /usr/lib/pkgconfig/opencv.pc
libopencv-core-dev: /usr/lib/pkgconfig/opencv.pc
marcolz:/>

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: libopencv-dev 2.3.1-7
ProcVersionSignature: Ubuntu 3.5.0-34.55~precise1-generic 3.5.7.13
Uname: Linux 3.5.0-34-generic x86_64
ApportVersion: 2.0.1-0ubuntu17.3
Architecture: amd64
Date: Thu Jun 27 10:56:13 2013
InstallationMedia: Ubuntu 12.04.2 LTS "Precise Pangolin" - Release amd64 (20130213)
MarkForUpload: True
ProcEnviron:
 TERM=screen
 PATH=(custom, no user)
 LANG=C
 SHELL=zsh
SourcePackage: opencv
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Marc Olzheim (zlo-zlo)]

In 2.4.8+dfsg1-2ubuntu1 this has been "fixed" by no longer shipping a .pc file.

[Steffen Hemer (s-hemer)]

This one is still valid for libopencv-dev 4.2.0+dfsg-5 in focal! Now with multiarch path but still:

/usr/lib/x86_64-linux-gnu/pkgconfig/opencv4.pc:
 includedir_old=${prefix}/include/opencv4/opencv
 includedir_new=${prefix}/include/opencv4

But there is only
/usr/include/opencv4/opencv2
as an include folder