TBR: Revert "jiri: The jiri script must put $JIRI_ROOT/.jiri_root/bin in PATH before invoking the jiri binary."

This reverts commit ebde984135221e5fc900e345543165c381359838.

Change-Id: I347b9e45f63723f6d339aeec665cc7e75487c659
diff --git a/cmd/jiri/scripts/jiri b/cmd/jiri/scripts/jiri
index 9834583..6684669 100755
--- a/cmd/jiri/scripts/jiri
+++ b/cmd/jiri/scripts/jiri
@@ -57,9 +57,5 @@
   fatal "${JIRI_ROOT}/.jiri_root/bin/jiri is not executable"
 fi
 
-# Add $JIRI_ROOT/.jiri_root/bin to PATH, so that the jiri binary can find the
-# subcommand binaries.
-export PATH="${JIRI_ROOT}/.jiri_root/bin:${PATH}"
-
 # Execute the jiri binary.
 exec "${JIRI_ROOT}/.jiri_root/bin/jiri" "$@"
diff --git a/scripts/jiri b/scripts/jiri
index 9834583..6684669 100755
--- a/scripts/jiri
+++ b/scripts/jiri
@@ -57,9 +57,5 @@
   fatal "${JIRI_ROOT}/.jiri_root/bin/jiri is not executable"
 fi
 
-# Add $JIRI_ROOT/.jiri_root/bin to PATH, so that the jiri binary can find the
-# subcommand binaries.
-export PATH="${JIRI_ROOT}/.jiri_root/bin:${PATH}"
-
 # Execute the jiri binary.
 exec "${JIRI_ROOT}/.jiri_root/bin/jiri" "$@"