v0.15.2 (2020-07-23)

This minor release includes two new features:

• Spack install verbosity is decreased, and more debug levels are added (#17546)
• The $spack/share/spack/keys directory contains public keys that may be optionally trusted for public binary mirrors (#17684)

This release also includes several important fixes:

• MPICC and related variables are now cleand in the build environment (#17450)
• LLVM flang only builds CUDA offload components when +cuda (#17466)
• CI pipelines no longer upload user environments that can contain secrets to the internet (#17545)
• CI pipelines add bootstrapped compilers to the compiler config (#17536)
• spack buildcache list does not exit on first failure and lists later mirrors (#17565)
• Apple's "gcc" executable that is an apple-clang compiler does not generate a gcc compiler config (#17589)
• Mixed compiler toolchains are merged more naturally across different compiler suffixes (#17590)
• Cray Shasta platforms detect the OS properly (#17467)
• Additional more minor fixes.