Analyse following RPM build log snippet. Describe contents accurately, without speculation or suggestions for resolution.            
Your analysis must be as concise as possible, while keeping relevant information intact.
Snippet: 
error: Bad exit status from /var/tmp/rpm-tmp.4JLmug (%build)
    Bad exit status from /var/tmp/rpm-tmp.4JLmug (%build)
RPM build errors:
Child return code was: 1

The build failed during %build phase.