Properly drop overwritten ex data #618

Job	Run time
rustfmt	13s
Test (stable)	7s
clippy	42s
Cross build from macOS to Linux (x86_64-unknown-linux-gnu)	3m 1s
Cross build from macOS to Linux (FIPS) (x86_64-unknown-linux-gnu)	5m 29s
Test features	1m 13s
Test (macos-x86_64)	1s
Test FIPS integration	1m 50s
Test (arm-android)	1m 13s
Test (arm64-android)	1m 13s
Test (i686-android)	1m 11s
Test (x86_64-android)	49s
Test (aarch64-ios)	1s
Test (aarch64-ios-sim)	1s
Test (x86_64-ios)	1s
Test (i686-linux)	1m 27s
Test (arm-linux)	1m 12s
Test (aarch64-linux)	1m 13s
Test (x86_64-musl)	1s
Test (x86_64-mingw)	1s
Test (i686-msvc)	51s
Test (x86_64-msvc)	1s
	21m 51s

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