sccache test failure when ccache is installed

Whenever ccache is present in fedora, running a C or C++ unittest, it fails consistently. I assume CC is set, and for testcases we should probably unset it - that interferes with sccache.

Not sure if we need detection logic for that or not.

sccache: Starting the server...
test test_sccache_command ... FAILED

failures:

---- test_sccache_command stdout ----
[2021-05-05T06:50:28Z TRACE system::harness] sccache --stop-server
[2021-05-05T06:50:28Z TRACE system] start server
[2021-05-05T06:50:28Z TRACE system] run_sccache_command_test: gcc
[2021-05-05T06:50:28Z TRACE system] fs::copy("tests/test.c", "/tmp/sccache_system_testUPZyWN/test.c")
[2021-05-05T06:50:28Z TRACE system] fs::copy("tests/test_err.c", "/tmp/sccache_system_testUPZyWN/test_err.c")
[2021-05-05T06:50:28Z TRACE system] compile
thread 'test_sccache_command' panicked at 'Unexpected failure.
code-2
stderr=```sccache: error: failed to execute compile
sccache: caused by: Compiler not supported: "/usr/bin/ccache: invalid option -- \'E\'\nUsage:\n    ccache [options]\n    ccache compiler [compiler options]\n    compiler [compiler options]          (via symbolic link)\n\nCommon options:\n    -c, --cleanup              delete old files and recalculate size counters\n                               (normally not needed as this is done\n                               automatically)\n    -C, --clear                clear the cache completely (except configuration)\n        --config-path PATH     operate on configuration file PATH instead of the\n                               default\n    -d, --directory PATH       operate on cache directory PATH instead of the\n                               default\n        --evict-older-than AGE remove files older than AGE (unsigned integer\n                               with a d (days) or s (seconds) suffix)\n    -F, --max-files NUM        set maximum number of files in cache to NUM (use\n                               0 for no limit)\n    -M, --max-size SIZE        set maximum size of cache to SIZE (use 0 for no\n                               limit); available suffixes: k, M, G, T (decimal)\n                               and Ki, Mi, Gi, Ti (binary); default suffix: G\n    -X, --recompress LEVEL     recompress the cache to level LEVEL (integer or\n                               \"uncompressed\") using the Zstandard algorithm;\n                               see \"Cache compression\" in the manual for details\n    -o, --set-config KEY=VAL   set configuration item KEY to value VAL\n    -x, --show-compression     show compression statistics\n    -p, --show-config          show current configuration options in\n                               human-readable format\n    -s, --show-stats           show summary of configuration and statistics\n                               counters in human-readable format\n    -z, --zero-stats           zero statistics counters\n\n    -h, --help                 print this help text\n    -V, --version              print version and copyright information\n\nOptions for scripting or debugging:\n        --checksum-file PATH   print the checksum (64 bit XXH3) of the file at\n                               PATH\n        --dump-manifest PATH   dump manifest file at PATH in text format\n        --dump-result PATH     dump result file at PATH in text format\n        --extract-result PATH  extract data stored in result file at PATH to the\n                               current working directory\n    -k, --get-config KEY       print the value of configuration key KEY\n        --hash-file PATH       print the hash (160 bit BLAKE3) of the file at\n                               PATH\n        --print-stats          print statistics counter IDs and corresponding\n                               values in machine-parsable format\n\nSee also the manual on <https://ccache.dev/documentation.html>.\n"

command="/media/supersonic1t/projects/sccache/target/debug/sccache" "/usr/bin/ccache" "-c" "test.c" "-o" "test.o" code=2 stdout=``` stderr=sccache: error: failed to execute compile sccache: caused by: Compiler not supported: "/usr/bin/ccache: invalid option -- \'E\'\nUsage:\n ccache [options]\n ccache compiler [compiler options]\n compiler [compiler options] (via symbolic link)\n\nCommon options:\n -c, --cleanup delete old files and recalculate size counters\n (normally not needed as this is done\n automatically)\n -C, --clear clear the cache completely (except configuration)\n --config-path PATH operate on configuration file PATH instead of the\n default\n -d, --directory PATH operate on cache directory PATH instead of the\n default\n --evict-older-than AGE remove files older than AGE (unsigned integer\n with a d (days) or s (seconds) suffix)\n -F, --max-files NUM set maximum number of files in cache to NUM (use\n 0 for no limit)\n -M, --max-size SIZE set maximum size of cache to SIZE (use 0 for no\n limit); available suffixes: k, M, G, T (decimal)\n and Ki, Mi, Gi, Ti (binary); default suffix: G\n -X, --recompress LEVEL recompress the cache to level LEVEL (integer or\n \"uncompressed\") using the Zstandard algorithm;\n see \"Cache compression\" in the manual for details\n -o, --set-config KEY=VAL set configuration item KEY to value VAL\n -x, --show-compression show compression statistics\n -p, --show-config show current configuration options in\n human-readable format\n -s, --show-stats show summary of configuration and statistics\n counters in human-readable format\n -z, --zero-stats zero statistics counters\n\n -h, --help print this help text\n -V, --version print version and copyright information\n\nOptions for scripting or debugging:\n --checksum-file PATH print the checksum (64 bit XXH3) of the file at\n PATH\n --dump-manifest PATH dump manifest file at PATH in text format\n --dump-result PATH dump result file at PATH in text format\n --extract-result PATH extract data stored in result file at PATH to the\n current working directory\n -k, --get-config KEY print the value of configuration key KEY\n --hash-file PATH print the hash (160 bit BLAKE3) of the file at\n PATH\n --print-stats print statistics counter IDs and corresponding\n values in machine-parsable format\n\nSee also the manual on https://ccache.dev/documentation.html.\n"

', /home/bernhard/.cargo/registry/src/github.com-1ecc6299db9ec823/assert_cmd-1.0.2/src/assert.rs:158:13
stack backtrace:
   0: rust_begin_unwind
             at /rustc/2fd73fabe469357a12c2c974c140f67e7cdd76d0/library/std/src/panicking.rs:493:5
   1: std::panicking::begin_panic_fmt
             at /rustc/2fd73fabe469357a12c2c974c140f67e7cdd76d0/library/std/src/panicking.rs:435:5
   2: assert_cmd::assert::Assert::success
             at /home/bernhard/.cargo/registry/src/github.com-1ecc6299db9ec823/assert_cmd-1.0.2/src/assert.rs:158:13
   3: system::test_basic_compile
             at ./tests/system.rs:109:5
   4: system::run_sccache_command_tests
             at ./tests/system.rs:363:5
   5: system::test_sccache_command
             at ./tests/system.rs:440:13
   6: system::test_sccache_command::{{closure}}
             at ./tests/system.rs:417:1
   7: core::ops::function::FnOnce::call_once
             at /home/bernhard/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/function.rs:227:5
   8: core::ops::function::FnOnce::call_once
             at /rustc/2fd73fabe469357a12c2c974c140f67e7cdd76d0/library/core/src/ops/function.rs:227:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

failures:
    test_sccache_command

paritytech / cachepot

sccache test failure when ccache is installed #69