Inherit essential environment variables in tests.

Note: it could be better to generalize this in SCons/Platform/posix.py
instead of just patching the tests.

diff --git a/SCons/ActionTests.py b/SCons/ActionTests.py
--- a/SCons/ActionTests.py
+++ b/SCons/ActionTests.py
@@ -98,6 +98,7 @@ outfile2 = test.workpath('outfile2')
 pipe_file = test.workpath('pipe.out')
 
 scons_env = SCons.Environment.Environment()
+scons_env['ENV']['PATH'] += os.environ['PATH']
 
 # Capture all the stuff the Actions will print,
 # so it doesn't clutter the output.
@@ -1090,6 +1091,8 @@ class CommandActionTestCase(unittest.TestCase):
         except AttributeError:
             env = Environment()
 
+        env = Environment(ENV={'PATH': os.environ['PATH']})
+
         cmd1 = r'%s %s %s xyzzy' % (_python_, act_py, outfile)
 
         act = SCons.Action.CommandAction(cmd1)
@@ -1884,7 +1887,7 @@ class ListActionTestCase(unittest.TestCase):
                     f.write("class2b\n")
 
         act = SCons.Action.ListAction([cmd2, function2, class2a(), class2b])
-        r = act([], [], Environment(out=outfile))
+        r = act([], [], Environment(out=outfile, ENV={'PATH' : os.getenv('PATH')}))
         assert isinstance(r.status, class2b), r.status
         c = test.read(outfile, 'r')
         assert c == "act.py: 'syzygy'\nfunction2\nclass2a\nclass2b\n", c
@@ -1948,7 +1951,7 @@ class LazyActionTestCase(unittest.TestCase):
         a([], [], env=Environment(BAR=f, s=self))
         assert self.test == 1, self.test
         cmd = r'%s %s %s lazy' % (_python_, act_py, outfile)
-        a([], [], env=Environment(BAR=cmd, s=self))
+        a([], [], env=Environment(BAR=cmd, s=self, ENV={'PATH' : os.getenv('PATH')}))
         c = test.read(outfile, 'r')
         assert c == "act.py: 'lazy'\n", c
 
diff --git a/SCons/SConfTests.py b/SCons/SConfTests.py
--- a/SCons/SConfTests.py
+++ b/SCons/SConfTests.py
@@ -71,7 +71,9 @@ class SConfTestCase(unittest.TestCase):
         # and we need a new environment, cause references may point to
         # old modules (well, at least this is safe ...)
         self.scons_env = self.Environment.Environment()
-        self.scons_env.AppendENVPath('PATH', os.environ['PATH'])
+        # Inherit the OS environment to get essential variables.
+        inherited_env = os.environ.copy()
+        self.scons_env['ENV'] = inherited_env
 
         # we want to do some autodetection here
         # this stuff works with
guix/log/etc/release-manifest.scm?id=370468c5471a8bbb9862f8ec0d6b7aa3daa436cb&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2023-03-30 11:14:53 +0200'>2023-03-30</span></td><td><a href='/guix/commit/etc/release-manifest.scm?id=4ba06192aa9000f25946df9ed7cad2d7cbb6f2c4'>maint: Add icecat to the release manifest.</a><span class='msg-avail'>...<span class='msg-tooltip'>* etc/release-manifest.scm (%system-packages): Uncomment icecat.
</span></span></td><td>Andreas Enge</td></tr>
<tr><td><span title='2023-02-05 06:56:42 +0100'>2023-02-05</span></td><td><a href='/guix/commit/etc/release-manifest.scm?id=c3e61c8c1f5ce867408ba7a113882a4b0ad5b2cb'>gnu: Rename 'guile-3.0/fixed' to 'guile-3.0/pinned'.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/guile.scm: Rename variable 'guile-3.0/fixed' to
'guile-3.0/pinned', add deprecation.
* etc/release-manifest.scm (%packages-to-cross-build): Replace
'guile-3.0/fixed' with 'guile-3.0/pinned'.
* gnu/packages/autotools.scm (make-autoconf-wrapper)[inputs]: Likewise.
* gnu/packages/commencement.scm (guile-final): Likewise.

Signed-off-by: Liliana Marie Prikler &lt;liliana.prikler@gmail.com&gt;
</span></span></td><td>Simon Tournier</td></tr>
<tr><td><span title='2022-11-28 13:51:51 +0100'>2022-11-28</span></td><td><a href='/guix/commit/etc/release-manifest.scm?id=1bc9d5222f9053fd0ace7b92df0ef9548707cf41'>maint: Leave 'gcc-toolchain' out for i586-gnu.</a><span class='msg-avail'>...<span class='msg-tooltip'>This is a temporary measure to work around the fact that we're currently
lacking the necessary CPU power and human power to build everything up
to 'gcc-toolchain'.

* etc/release-manifest.scm (%base-packages/hurd): Comment out
"gcc-toolchain" for now.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2022-10-25 10:10:06 +0100'>2022-10-25</span></td><td><a href='/guix/commit/etc/release-manifest.scm?id=be9b213c75e903d999a6caedab1c6d4b3ffd623b'>maint: Tweak release manifest special case for armhf-linux.</a><span class='msg-avail'>...<span class='msg-tooltip'>Don't remove the emacs package, as it does build and substitutes are
available. Do remove the guix package though, as it doesn't build due to Guile
memory issues while compiling the package modules.

* etc/release-manifest.scm (%base-packages/armhf): Don't replace the emacs
package, remove the guix package.
(%base-manifest): Remove FIXME comment as %base-packages/armhf doesn't relate
to build power.
</span></span></td><td>Christopher Baines</td></tr>
<tr><td><span title='2022-09-01 18:31:26 +0200'>2022-09-01</span></td><td><a href='/guix/commit/etc/release-manifest.scm?id=fe149b01d0b65f421602f8bc794a926434f5d9a9'>maint: Ignore cross-compilation to x86.</a><span class='msg-avail'>...<span class='msg-tooltip'>This is consistent with what's done by 'cross-jobs' in (gnu ci).

* etc/release-manifest.scm (%cross-manifest): Remove "x86_64-linux-gnu"
and "i686-linux-gnu" from the list returned by 'targets'.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2022-05-25 09:27:25 +0200'>2022-05-25</span></td><td><a href='/guix/commit/etc/release-manifest.scm?id=dab819d5c4c55609efae098c8e3c2f2757c34e5b'>Move (gnu platform) and (gnu platforms ...) to guix/.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/platform.scm:
* gnu/platforms/arm.scm:
* gnu/platforms/hurd.scm:
* gnu/platforms/mips.scm:
* gnu/platforms/powerpc.scm:
* gnu/platforms/riscv.scm:
* gnu/platforms/s390.scm:
* gnu/platforms/x86.scm: Move to guix/.

* Makefile.am:
* doc/guix.texi (Porting to a New Platform):
* etc/release-manifest.scm:
* gnu/ci.scm:
* gnu/image.scm:
* gnu/local.mk:
* gnu/packages/bioinformatics.scm:
* gnu/packages/bootstrap.scm:
* gnu/packages/cross-base.scm:
* gnu/packages/instrumentation.scm:
* gnu/packages/linux.scm:
* gnu/system/image.scm:
* gnu/system/images/hurd.scm:
* gnu/system/images/novena.scm:
* gnu/system/images/pine64.scm:
* gnu/system/images/pinebook-pro.scm:
* gnu/system/images/rock64.scm:
* guix/scripts/build.scm:
* guix/scripts/system.scm:
* guix/self.scm: Update (gnu platform...) to (guix platform...).

Signed-off-by: Mathieu Othacehe &lt;othacehe@gnu.org&gt;
</span></span></td><td>Josselin Poiret</td></tr>
<tr><td><span title='2022-05-22 15:15:33 +0200'>2022-05-22</span></td><td><a href='/guix/commit/etc/release-manifest.scm?id=dd970122ddf3679482f658f73dd68307496c6215'>ci: Do not rely on hardcoded cross-targets lists.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/ci.scm (%cross-targets): Remove it ...
(cross-jobs): ... and use the targets procedure instead.
* etc/release-manifest.scm: Adapt it.

Signed-off-by: Mathieu Othacehe &lt;othacehe@gnu.org&gt;
</span></span></td><td>Mathieu Othacehe</td></tr>