Skip tests that rely on the `amhello' tarball that comes with Automake.
That tarball's `configure' uses #!/bin/sh, but we can't easily patch it.

diff --git a/t/amhello-binpkg.sh b/t/amhello-binpkg.sh
index fa88cc6..d988cee 100755
--- a/t/amhello-binpkg.sh
+++ b/t/amhello-binpkg.sh
@@ -17,6 +17,7 @@
 # Test an example from the manual about the 'amhello' package:
 # using DESTDIR to build simple, no-frills binary packages.
 
+exit 77
 am_create_testdir=empty
 . ./defs || exit 1
 
diff --git a/t/amhello-cflags.sh b/t/amhello-cflags.sh
index 666011f..2a95e3c 100755
--- a/t/amhello-cflags.sh
+++ b/t/amhello-cflags.sh
@@ -18,6 +18,7 @@
 # using VPATH builds to configure the same package with different
 # options.
 
+exit 77
 am_create_testdir=empty
 required=gcc
 . ./defs || exit 1
diff --git a/t/amhello-cross-compile.sh b/t/amhello-cross-compile.sh
index 708abda..2ee4292 100755
--- a/t/amhello-cross-compile.sh
+++ b/t/amhello-cross-compile.sh
@@ -17,6 +17,7 @@
 # Test an example from the manual about the 'amhello' package:
 # cross-compiling a package from Linux/Unix to MinGW.
 
+exit 77
 am_create_testdir=empty
 required=i586-mingw32msvc-gcc
 . ./defs || exit 1
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<div class='path'>path: <a href='/guix/log/?id=2a08065b051e42836cd46da0876ac2b2b6ee7733'>root</a>/<a href='/guix/log/tests?id=2a08065b051e42836cd46da0876ac2b2b6ee7733'>tests</a>/<a href='/guix/log/tests/substitute.scm?id=2a08065b051e42836cd46da0876ac2b2b6ee7733'>substitute.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/tests/substitute.scm?id=2a08065b051e42836cd46da0876ac2b2b6ee7733&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2022-09-28 22:28:27 +0200'>2022-09-28</span></td><td><a href='/guix/commit/tests/substitute.scm?id=8bd4126917f59f4af9a4323c3d5699201862dca2'>substitute: Retry downloading when a nar is unavailable.</a><span class='msg-avail'>...<span class='msg-tooltip'>Fixes &lt;https://issues.guix.gnu.org/57978&gt;
Reported by Attila Lendvai &lt;attila@lendvai.name&gt;.

Previously, if a narinfo was available but its corresponding nar was
missing (for instance because the narinfo was cached and the server
became unreachable in the meantime), 'guix substitute --substitute'
would try to download the nar from its preferred location and abort when
that fails.  This change forces one retry with each of the URLs.

* guix/scripts/substitute.scm (download-nar): Do not catch
'http-get-error?' exceptions.
(system-error?, network-error?, process-substitution/fallback): New
procedures.
(process-substitution): Call 'process-substitution/fallback' upon
'network-error?'.
* tests/substitute.scm ("substitute, first URL has narinfo but lacks nar, second URL unauthorized")
("substitute, first URL has narinfo but nar is 404, both URLs authorized")
("substitute, first URL has narinfo but nar is 404, one URL authorized")
("substitute, narinfo is available but nar is missing"): New tests.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2022-09-24 17:59:04 +0200'>2022-09-24</span></td><td><a href='/guix/commit/tests/substitute.scm?id=08023bcab35faafcf3e9c77babe910d9ece240d2'>substitute: Test behavior with unroutable substitute server addresses.</a><span class='msg-avail'>...<span class='msg-tooltip'>* tests/substitute.scm (%unroutable-substitute-url): New variable.
("query narinfo signed with authorized key, unroutable URL first")
("substitute, authorized key, first substitute URL is unroutable"): New
tests.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2022-02-14 11:23:56 +0100'>2022-02-14</span></td><td><a href='/guix/commit/tests/substitute.scm?id=6adce1538d2df6fa2d68abc13ae94e2fa826d124'>publish: Do not sign the URL/Compression/FileSize narinfo fields.</a><span class='msg-avail'>...<span class='msg-tooltip'>This will allow mirror operators to alter these non-normative bits of a
narinfo without having to resign narinfos.

* guix/scripts/publish.scm (narinfo-string): Remove
URL/Compression/FileSize from BASE-INFO.  Move them after "Signature".
* tests/publish.scm ("/*.narinfo")
("/*.narinfo with properly encoded '+' sign")
("/*.narinfo with lzip + gzip")
("with cache, lzip + gzip"): Adjust accordingly.
* tests/substitute.scm ("query narinfo with signature over relevant subset"):
New test.
</span></span></td><td>Ludovic Courtès</td></tr>