test-update-copyright requires perl

[Eric Blake]

I just noticed a problem.  update-copyright is a perl script only intended for 
maintainer use, which is fine, since only maintainers are required to have perl 
installed (after all, we already know that maintainers have perl by virtue of 
the fact that they are running autoconf).  But, as explicitly permitted by the 
GNU standards, end users need not have good enough perl.  In other words, 
blindly including test-update-copyright as part of 'make check' in any package 
that bootstrapped via 'gnulib-tool --with-tests' can lead to spurious failures 
for some end users because the test is assuming more than the end user is 
required to have.

One option is to just relax test-update-copyright.sh to gracefully skip the 
test if perl is not found or can't successfully perform copyright updates.  
Another option is to figure out a way to make gnulib tool distinguish between 
tests of end-user code (most tests) vs. tests of maintainer-only tools (test-
update-copyright, test-vc-list-files, ...) and set things up so that maintainer 
tool tests are only run by 'make distcheck' rather than 'make check'.  
Actually, even 'make distcheck' might be wrong, since that is supposed to work 
without autotools; and 'make maintainer-check' as part of maint.mk may be a 
better place.  Any other ideas, or an approach for a patch along any of these 
lines?

For the record, I discovered this because 'perl -ei' fails on cygwin 1.5 [but 
works in cygwin 1.7] because of older cygwin's inability to delete in-use files:

--- -   2009-08-14 14:25:35.060804000 -0600
+++ update-copyright.test-ex-stderr     2009-08-14 14:25:35.013932200 -0600
@@ -1,2 +1,7 @@
-update-copyright.test-ex.4: warning: FSF copyright statement not found
-update-copyright.test-ex.5: warning: FSF copyright statement not found
+Can't do inplace edit on update-copyright.test-ex.1: Permission denied.
+Can't do inplace edit on update-copyright.test-ex.2: Permission denied.
+Can't do inplace edit on update-copyright.test-ex.3: Permission denied.
+Can't do inplace edit on update-copyright.test-ex.4: Permission denied.
+Can't do inplace edit on update-copyright.test-ex.5: Permission denied.
+Can't do inplace edit on update-copyright.test-ex.6: Permission denied.
+Can't do inplace edit on update-copyright.test-ex.7: Permission denied.
FAIL: test-update-copyright.sh

-- 
Eric Blake