with fc25,use mock to build libcap-2.25-2.fc25.src.rpm has build erro,bug use rpmbuild  -ba libcap-2.25-2.fc25.src.rpm it's ok, why?

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# mock mock libcap-2.25-2.fc25.src.rpm --resultdir=/home/mock/mock-result-3


Complete!
Finish: build setup for libcap-2.25-2.fc25.src.rpm
Start: rpmbuild libcap-2.25-2.fc25.src.rpm
构建目标平台：x86_64
为目标x86_64构建
执行(%prep): /bin/sh -e /var/tmp/rpm-tmp.LJ6xhX
+ umask 022
+ cd /builddir/build/BUILD
+ cd /builddir/build/BUILD
+ rm -rf libcap-2.25
+ /usr/bin/gzip -dc /builddir/build/SOURCES/libcap-2.25.tar.gz
+ /usr/bin/tar -xof -
+ STATUS=0
+ '[' 0 -ne 0 ']'
+ cd libcap-2.25
+ /usr/bin/chmod -Rf a+rX,u+w,g-w,o-w .
+ echo 'Patch #0 (libcap-2.25-buildflags.patch):'
Patch #0 (libcap-2.25-buildflags.patch):
+ /usr/bin/patch --no-backup-if-mismatch -p1 --fuzz=0
patching file Make.Rules
+ exit 0
执行(%build): /bin/sh -e /var/tmp/rpm-tmp.9zv7YR
+ umask 022
+ cd /builddir/build/BUILD
+ cd libcap-2.25
+ make prefix=/usr lib=lib64 LIBDIR=/usr/lib64 SBINDIR=/usr/sbin INCDIR=/usr/include MANDIR=/usr/share/man PKGCONFIGDIR=/usr/lib64/pkgconfig/
make -C libcap all
make[1]: Entering directory '/builddir/build/BUILD/libcap-2.25/libcap'
=> making cap_names.list.h from /builddir/build/BUILD/libcap-2.25/libcap/../libcap/include/uapi/linux/capability.h
perl -e 'while ($l=<>) { if ($l =~ /^\#define[ \t](CAP[_A-Z]+)[ \t]+([0-9]+)\s+$/) { $tok=$1; $val=$2; $tok =~ tr/A-Z/a-z/; print "{\"$tok\",$val},\n"; } }' /builddir/build/BUILD/libcap-2.25/libcap/../libcap/include/uapi/linux/capability.h | fgrep -v 0x > cap_names.list.h
/bin/sh: perl: command not found
Makefile:47: recipe for target 'cap_names.list.h' failed
make[1]: Leaving directory '/builddir/build/BUILD/libcap-2.25/libcap'
make[1]: *** [cap_names.list.h] Error 1
Makefile:12: recipe for target 'all' failed
make: *** [all] Error 2


RPM 构建错误：
错误：/var/tmp/rpm-tmp.9zv7YR (%build) 退出状态不好
    /var/tmp/rpm-tmp.9zv7YR (%build) 退出状态不好
ERROR: Exception(libcap-2.25-2.fc25.src.rpm) Config(redflag-9-x86_64) 1 minutes 33 seconds
INFO: Results and/or logs in: /home/mock/mock-result-3/
INFO: Cleaning up build root ('cleanup_on_failure=True')
Start: clean chroot
Finish: clean chroot
ERROR: Command failed. See logs for output.
 # bash --login -c /usr/bin/rpmbuild -bb --target x86_64 --nodeps /builddir/build/SPECS/libcap.spec



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2.rpmbuild -ba libcap-2.25-2.fc25.src.rpm

can build sucess.



why so？