Fixed a bashism with the use of $RANDOM in hgeditor.
The variable $RANDOM is not POSIX so a portable /bin/sh may not define
it. When creating a directory with a random name it's better to use
mktemp, which, even though is not POSIX, exists in common Unixes
including Linux, OpenBSD, FreeBSD and MacOS X.
invoking hg diff --nodates --change 1:
diff -r 4bb65dda5db4 -r e9b286083166 file.txt
--- a/file.txt
+++ b/file.txt
@@ -1,1 +1,1 @@
-first
+second
invoking hg diff --nodates --change e9b286083166:
diff -r 4bb65dda5db4 -r e9b286083166 file.txt
--- a/file.txt
+++ b/file.txt
@@ -1,1 +1,1 @@
-first
+second
invoking hg diff --nodates --change 6:
diff -r e8a0797e73a6 -r aa9873050139 file.txt
--- a/file.txt
+++ b/file.txt
@@ -6,6 +6,6 @@
5
6
7
-8
+y
9
10
EOF