tests: improve portability by no longer using the flag [tar --force-local]

A different way of making sure the path is not interpreted as a URL is to never
give this path to [tar], instead making tar read from stdin.

tests/test-issue6528.t

@@ -177,14 +177,7 b" It's a tarball because unbundle might ma"
   $ cd ..
   $ mkdir repo-to-fix
   $ cd repo-to-fix
-#if windows
-tar interprets `:` in paths (like `C:`) as being remote, force local on Windows
-only since some versions of tar don't have this flag.
-
-  $ tar --force-local -xf $TESTDIR/bundles/issue6528.tar
-#else
-  $ tar xf $TESTDIR/bundles/issue6528.tar
-#endif
+  $ tar -x < $TESTDIR/bundles/issue6528.tar
 
 Check that the issue is present
 (It is currently not present with rhg but will be when optimizations are added
@@ -285,14 +278,7 b' Try the using the report options'
   $ cd ..
   $ mkdir repo-to-fix-report
   $ cd repo-to-fix
-#if windows
-tar interprets `:` in paths (like `C:`) as being remote, force local on Windows
-only since some versions of tar don't have this flag.
-
-  $ tar --force-local -xf $TESTDIR/bundles/issue6528.tar
-#else
-  $ tar xf $TESTDIR/bundles/issue6528.tar
-#endif
+  $ tar -x < "$TESTDIR"/bundles/issue6528.tar
 
   $ hg debug-repair-issue6528 --to-report $TESTTMP/report.txt
   found affected revision 1 for filelog 'data/D.txt.i'
@@ -379,14 +365,7 b' Try it with a non-inline revlog'
 
   $ mkdir repo-to-fix-not-inline
   $ cd repo-to-fix-not-inline
-#if windows
-tar interprets `:` in paths (like `C:`) as being remote, force local on Windows
-only since some versions of tar don't have this flag.
-
-  $ tar --force-local -xf $TESTDIR/bundles/issue6528.tar
-#else
-  $ tar xf $TESTDIR/bundles/issue6528.tar
-#endif
+  $ tar -x < "$TESTDIR"/bundles/issue6528.tar
   $ echo b >> b.txt
   $ hg commit -qm "inline -> separate"
   $ find .hg -name *b.txt.d

tests/test-revlog.t

@@ -73,7 +73,7 b' This is what we did to produce the repo '
 - hg commit -Am_
 - remove some cache files
 
-  $ tar --force-local -xf "$TESTDIR"/bundles/test-revlog-diff-relative-to-nullrev.tar
+  $ tar -x < "$TESTDIR"/bundles/test-revlog-diff-relative-to-nullrev.tar
   $ cd nullrev-diff
   $ hg debugdeltachain a
       rev      p1      p2  chain# chainlen     prev   delta       size    rawsize  chainsize     ratio   lindist extradist extraratio   readsize largestblk rddensity srchunks