Function get_source_time 

pub fn get_source_time() -> Result<u64, String>

Gets the modification time of the source code.

Reads the SOURCE_DATE_EPOCH env var if set. Otherwise, runs git to get the value.

Errors

Returns an error when:

• SOURCE_DATE_EPOCH is non-empty and cannot be parsed as an u64
• it failed to execute git
• git exited with non-zero status
• git wrote stdout data in an unexpected format