[ruby-core:66967] undefined symbol: rb_Digest_SHA1_Init

Hello,

While trying to install redmine, I got the "undefined symbol: 
rb_Digest_SHA1_Init" (and others) which has been reported several times 
:

https://www.google.fr/search?q=rb_Digest_SHA1_Init&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:fr:official&client=firefox-a&channel=fflb&gfe_rd=cr&ei=WJ-RVN2cD63j8wfW6IGoAw

I tried all the solutions suggested, but it didn't work. Maybe I should 
have run make distclean;./configure again, but instead I found that e.g. 
"sha1.o" was missing in $OBJS in ext/digest/sha1/Makefile.

While it sounds normal if the configure step does not include support 
for missing libraries, here it just happily compiles and later reports a 
linker fault on execution (objdump -t showed the symbol was undefined).

Simply adding sha1.o in the Makefile and running make agian fixed the 
problem, but in the meantilme I also had installed libssl, which I 
suspect would have also fixed the problem if I re-ran configure.

I think configure should fail earlier if the problem comes from here. I 
can provide more details if needed. My platform was a RHEL 6.5

Thanks.