Bug 790261 - autogen.sh non-portable use of echo -n.
The reporter notes in particular that the -n option does not work appropriately on recent versions of macOS. From what I know, echo without any option is the most portable. But when options are needed, there are too many variants of the command out there, and printf becomes more reliable and consistent across platforms. It is more recent than echo and therefore non-portable for very very old platforms, but let's assume/hope that it old-enough for not being a problem anymore.
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