tests: make tests with temporary environment setting portable
With "dash" (as "/bin/sh" on Debian GNU/Linux), command execution in
"ENV=val foo bar" style doesn't work as expect in test script files,
if "foo" is user-defined function: it works fine, if "foo" is existing
commands like "hg".
09049042ab99 introduced tests for HGPLAIN and HGPLAINEXCEPT into
test-revset.t, and all of them are in such style.
This patch doesn't:
- add explicit unsetting for HGPLAIN and HGPLAINEXCEPT
they are already introduced by 09049042ab99
- write assignment and exporting in one line
"ENV=val; export ENV" for two or more environment variables in one
line causes failure of test-check-code-hg.t: it is recognized as
"don't export and assign at once" unfortunately.
$ hg init
$ touch a
$ hg add a
$ hg ci -m "a"
$ echo 123 > b
$ hg add b
$ hg diff --nodates
diff -r 3903775176ed b
--- /dev/null
+++ b/b
@@ -0,0 +1,1 @@
+123
$ hg diff --nodates -r tip
diff -r 3903775176ed b
--- /dev/null
+++ b/b
@@ -0,0 +1,1 @@
+123
$ echo foo > a
$ hg diff --nodates
diff -r 3903775176ed a
--- a/a
+++ b/a
@@ -0,0 +1,1 @@
+foo
diff -r 3903775176ed b
--- /dev/null
+++ b/b
@@ -0,0 +1,1 @@
+123
$ hg diff -r ""
hg: parse error: empty query
[255]
$ hg diff -r tip -r ""
hg: parse error: empty query
[255]