Enhance strip_trailing_separator to handle UNC and extended-length pa… #1196

Job	Run time
Tests in Containers (ci-jupyter-container, ubuntu-latest, mcr.microsoft.com/devcontainers/univers...	4m 17s
Tests in Containers (ci-homebrew-container, ubuntu-latest, homebrew/brew, x86_64-unknown-linux-musl)	3m 30s
Builds (macos-latest, x86_64-apple-darwin, yes)	2m 52s
Tests (macos-latest, x86_64-apple-darwin, yes)	12m 39s
Tests (macos-14, aarch64-apple-darwin, yes)	13m 34s
Builds (macos-14, aarch64-apple-darwin, yes)	1m 46s
Tests (windows-latest, x86_64-pc-windows-msvc, yes)	7m 7s
Env Tests (ci-poetry-custom, ubuntu-latest, x86_64-unknown-linux-musl)	2m 33s
Env Tests (ci-poetry-global, windows-latest, x86_64-pc-windows-msvc)	4m 41s
Env Tests (ci-poetry-project, ubuntu-latest, x86_64-unknown-linux-musl)	2m 35s
Env Tests (ci-poetry-custom, windows-latest, x86_64-pc-windows-msvc)	4m 42s
Builds (windows-latest, aarch64-pc-windows-msvc)	4m 48s
Env Tests (ci-poetry-global, ubuntu-latest, x86_64-unknown-linux-musl)	2m 27s
Tests (ubuntu-latest, x86_64-unknown-linux-musl, yes)	8m 37s
Builds (ubuntu-latest, x86_64-unknown-linux-musl, yes)	1m 58s
Env Tests (ci-poetry-project, windows-latest, x86_64-pc-windows-msvc)	4m 49s
Builds (windows-latest, x86_64-pc-windows-msvc)	4m 2s
	1h 26m 57s

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