The hooks' judge() built its private index and tree under `mktemp -d`, a POSIX /c/...
path in Git Bash, and passed it to native git.exe and python.exe through GIT_INDEX_FILE,
--prefix and the checker path. Hermes' Windows terminal exports MSYS_NO_PATHCONV=1 and
MSYS2_ARG_CONV_EXCL=*, so those paths arrived unconverted and the hook died
("Unable to create '/c/.../index.lock'") before any check ran. judge() now hands native
tools the `cygpath -m` spelling when cygpath exists; elsewhere nothing changes.
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