imath caching issue

[palemieux]

To replicate on Ubuntu:

git clone https://github.com/AcademySoftwareFoundation/openexr.git --depth 1
cd openexr
mkdir build
cd build/
cmake ..
make
cmake ..
make

results in the error:

/home/pal/Downloads/openexr/src/lib/OpenEXRCore/openexr_config.h:12:10: fatal error: Imath/ImathConfig.h: No such file or directory
   12 | #include <Imath/ImathConfig.h>
      |          ^~~~~~~~~~~~~~~~~~~~~

The issue seems to be related to:

openexr/cmake/OpenEXRSetup.cmake

Line 438 in cadf06b

set(_openexr_imath_inc_patch_key "${Imath_SOURCE_DIR}|${Imath_BINARY_DIR}")

Removing the caching seems to fix the issue:

    target_include_directories(Imath INTERFACE
      "$<BUILD_INTERFACE:${Imath_SOURCE_DIR}/src>")
    if(EXISTS "${_openexr_imath_gen_cfg}")
      target_include_directories(ImathConfig INTERFACE
        "$<BUILD_INTERFACE:${_openexr_imath_cfg_compat}>")

[cary-ilm]

Looks like this was a regression I introduced in #2376. I've got a patch coming shortly.

[cary-ilm]

Addressed in #2443